Systems and methods for processing hydrogen

ABSTRACT

The present disclosure provides a fuel cell comprising: an electrochemical circuit comprising an anode, a cathode, and an electrolyte between the anode and the cathode; a first channel comprising a first inlet and a first outlet, wherein the first channel is in fluid communication with the anode, wherein the first channel comprises one or more features, wherein the one or more features comprise (i) one or more cuts, (ii) one or more cutouts, (iii) one or more grooves, or (iv) any combination thereof; and a second channel comprising a second inlet and a second outlet, wherein the second channel is in fluid communication with the cathode.

CROSS REFERENCE

This application is a continuation of International Patent ApplicationNo. PCT/US22/40367, filed Aug. 15, 2022, which claims priority to U.S.patent application Ser. No. 17/589,287, filed Jan. 31, 2022, claimingthe benefit of U.S. Provisional Patent Application No. 63/234,137, filedAug. 17, 2021, each of which are incorporated herein by reference intheir entirety for all purposes.

BACKGROUND

Various systems may be powered using a fuel source. The fuel source mayhave a specific energy corresponding to an amount of energy stored orextractable per unit mass of fuel. The fuel source may be provided tothe various systems to enable such systems to generate energy (e.g.,electrical energy) and/or deliver power (e.g., for movement ortransportation purposes).

SUMMARY

Hydrogen can be leveraged as a clean energy source to power varioussystems. Hydrogen can provide a distinct advantage over other types offuel such as diesel, gasoline, or jet fuel, which have specific energiesof about 45 megajoules per kilogram (MJ/kg) (heat), or lithium-ionbatteries, which have a specific energy of about 0.95 MJ/kg(electrical). In contrast, hydrogen has a specific energy of over 140MJ/kg (heat). As such, 1 kg of hydrogen can provide the same amount ofenergy as about 3 kg of gasoline or kerosene. Thus, hydrogen as a fuelsource can help to reduce the amount of fuel (by mass) needed to providea comparable amount of energy as other traditional sources of fuel.Further, systems that use hydrogen as a fuel source (e.g., as acombustion reactant) generally produce benign or nontoxic byproductssuch as water while producing minimal or near zero carbon dioxide andnitrous oxide emissions, thereby reducing the environmental impacts ofvarious systems (e.g., modes of transportation) that use hydrogen as afuel source.

Recognized herein are various limitations with conventional systems andmethods for processing hydrogen and/or mixtures of hydrogen and nitrogento produce electrical energy. For example, commercially available fuelcells may exhibit degraded performance over time when processing sourcematerials comprising hydrogen and other impurities (e.g., gases such asammonia and/or nitrogen). Since hydrogen extracted from hydrogencarriers may comprise one or more other elements or compounds that cannegatively impact fuel cell performance (e.g., conversion efficiency ofa source material into electrical energy), commercially available fuelcells may require separation of hydrogen from other materials before thehydrogen is fed to a fuel cell, which can be time consuming and resourceintensive.

The present disclosure provides systems and methods to address at leastthe abovementioned shortcomings of conventional systems for processing asource material to generate electrical energy. The present applicationrelates generally to systems and methods for processing a sourcematerial (e.g., hydrogen and/or nitrogen) to produce energy (e.g.,electrical energy). The energy may be used to power a system such as avehicle. In some embodiments, the vehicle may comprise a drone, alight-duty vehicle, a heavy-duty vehicle, or a maritime vehicle. In someembodiments, the vehicle may be configured to be operated by a human ora computer. In some embodiments, the vehicle may be autonomous orsemi-autonomous. The source material may comprise hydrogen and otherelements or compounds. In some instances, the source material maycomprise a mixture of hydrogen and nitrogen. The source material may ormay not comprise other impurities. In some cases, the source materialmay be filtered before being provided to a fuel cell. Such filtering maybe used to remove carbon monoxide and/or ammonia from the sourcematerial. The systems and methods of the present disclosure may be usedto convert hydrogen mixtures into electrical energy without requiringfiltration or purification of hydrogen mixtures to remove nitrogenand/or ammonia.

In one aspect, the present disclosure provides a fuel cell forprocessing hydrogen to generate an electrical current. The fuel cell maycomprise an anode, a cathode, and a membrane between the anode and thecathode. In some embodiments, the anode may comprise an anode gasdiffusion layer with one or more channels for directing a sourcematerial to the anode to facilitate processing of the source material togenerate an electrical current. In some embodiments, the one or morechannels may comprise one or more surface features configured to (i)enhance a diffusion and transport of the source material through theanode gas diffusion layer and (ii) facilitate a purging of selectmaterials from the anode gas diffusion layer. In some embodiments, thesource material may comprise hydrogen and/or nitrogen. In someembodiments, the select materials may comprise at least nitrogen. Insome embodiments, the select materials may comprise one or moreimpurities or unconverted ammonia. In some embodiments, the one or morefeatures are configured to direct a flow of nitrogen from the anode gasdiffusion layer to out of the fuel cell such that nitrogen does notaccumulate in the anode gas diffusion layer.

In some embodiments, processing of the source material may comprise adissociation of one or more hydrogen molecules of the source materialinto one or more protons and one or more electrons. In some embodiments,the anode gas diffusion layer may comprise a felt material, a foammaterial, a cloth material, or a paper material. In some embodiments,the felt, foam, cloth, or paper material may be a carbon-based material(e.g., carbon fibers).

In some embodiments, the one or more surface features may comprise oneor more cuts or grooves on a surface of the one or more channels. Insome embodiments, the one or more cuts or grooves may extend across aportion of the surface of the one or more channels. In some embodiments,the one or more cuts or grooves may comprise two or more cuts or groovesthat are parallel to each other. In some embodiments, the one or morecuts or grooves may comprise two or more cuts or grooves that areperpendicular to each other. In some embodiments, the one or more cutsor grooves may comprise two or more cuts or grooves that are disposed atan angle relative to each other. The angle may range from 0 degrees toabout 90 degrees. In some embodiments, the one or more cuts or groovesmay comprise two or more cuts or grooves that intersect with each other.In some embodiments, the one or more cuts or grooves may comprise two ormore cuts or grooves that do not intersect. In some embodiments, the oneor more surface features may comprise one or more cutouts or openings ona surface of the one or more channels. In some embodiments, the one ormore cutouts or openings may extend across a portion of the surface ofthe one or more channels. In some embodiments, the one or more cutoutsor openings may comprise two or more cutouts or openings that areparallel to each other. In some embodiments, the one or more cutouts oropenings may comprise two or more cutouts or openings that areperpendicular to each other. In some embodiments, the one or morecutouts or openings may comprise two or more cutouts or openings thatare disposed at an angle relative to each other. In some embodiments,the angle may range from 0 degrees to about 90 degrees. In someembodiments, the one or more cutouts or openings may comprise two ormore cuts or grooves that intersect with each other. In someembodiments, the one or more cutouts or openings may comprise two ormore cutouts or openings that do not intersect. In some embodiments, afeature of the one or more features has a depth ranging from about 0.01millimeter (mm) to about 10 mm.

In some embodiments, the anode gas diffusion layer may comprise one ormore layers. In some embodiments, the one or more layers may comprisetwo or more layers. In some embodiments, at least one layer of the twoor more layers may comprise the one or more surface features. In someembodiments, the one or more surface features may comprise (i) one ormore cuts or grooves or (ii) one or more cutouts or openings. In someembodiments, the two or more layers may comprise a first layercomprising a first set of surface features and a second layer comprisinga second set of surface features. In some embodiments, the first set offeatures and the second set of features may comprise a same or similarset of features. In some embodiments, the first set of features and thesecond set of features may comprise different sets of features havingdifferent shapes, dimensions, positions, or orientations. In someembodiments, the first set of features and the second set of featuresmay overlap or partially overlap. In some embodiments, the first set offeatures and the second set of features may not or need not overlap.

In some embodiments, the cathode may comprise one or more air flowchannels. In some embodiments, the cathode may comprise a cathodecurrent collecting layer and a cathode gas diffusion layer. In someembodiments, the one or more air flow channels or a subset thereof maybe configured to function as a current collecting layer. In someembodiments, the anode may further comprise an anode current collectinglayer.

In another aspect, the present disclosure provides a fuel cell system.The fuel cell system may comprise a plurality of fuel cells, disclosedherein, arranged adjacent to or stacked on top of each other. Theplurality of fuel cells may comprise a fuel cell with an anode, acathode, and an electrolyte disposed between the anode and the cathode.In some embodiments, the anode may comprise an anode gas diffusion layerwith one or more channels for directing a source material through theanode to facilitate processing of the source material to generate anelectrical current. In some embodiments, the one or more channels maycomprise one or more surface features configured to (i) enhance adiffusion and transport of the source material through the anode gasdiffusion layer and (ii) facilitate a purging of select materials fromthe anode gas diffusion layer. In some embodiments, the fuel cell systemmay comprise at least one ammonia reformer or reactor in fluidcommunication with the plurality of fuel cells. In some embodiments, theat least one ammonia reformer or reactor is configured to (i) generatethe source material and (ii) provide the source material to the fuelcell. In some embodiments, the fuel cell system comprises a computerconfigured to operate the fuel cell to allow purging of nitrogen fromthe fuel cell while the fuel cell is generating electricity. In someembodiments, the computer configured to operate the fuel cell to allowcontinuous purging of nitrogen. In some embodiments, the fuel cellsystem further comprises one or more inlet ports configured to receivethe source material, wherein ammonia concentration in the sourcematerial is less than 1 parts per million (ppm). In some embodiments,the fuel cell system further comprises one or more exit ports configuredto direct unconverted hydrogen from the plurality of fuel cells to theat least one ammonia reformer or reactor for combustion heating.

In some aspects, the present disclosure provides a method for generatingelectricity using a fuel cell, comprising: reacting, using an ammoniareformer, ammonia to generate a first continuous stream comprisingnitrogen and hydrogen, wherein the ammonia reformer is in fluidcommunication with the fuel cell, the fuel cell comprising: anelectrochemical circuit comprising an anode, a cathode, and anelectrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features configured to (i) increase a hydrogenconsumption rate of the fuel cell, or (ii) increase an output voltage ofthe fuel cell at a same hydrogen consumption rate, when the firstcontinuous stream contacts the anode compared to an equivalent fuel celllacking the one or more features, wherein the one or more featurescomprise (1) one or more cuts, (2) one or more cutouts, (3) one or moregrooves, or (4) any combination thereof; and a second channel comprisinga second inlet and a second outlet, wherein the second channel is influid communication with the cathode; and directing the first continuousstream into the first channel via the first inlet so that the hydrogencontacts the anode; directing a second continuous stream comprisingoxygen into the second channel via the second inlet so that the oxygencontacts the cathode; and reacting the hydrogen and the oxygen, usingthe fuel cell, to generate electrical power.

In some embodiments, the one or more features increase the hydrogenconsumption rate of the fuel cell when the first continuous streamcontacts the anode compared to the equivalent fuel cell lacking the oneor more features.

In some embodiments, the one or more features increase the hydrogenconsumption rate by at least 5, 10, 20, 40, 60, 80, 100, 120, 140, 160,180, or 200%.

In some embodiments, the one or more features increase the hydrogenconsumption rate by at most 5, 10, 20, 40, 60, 80, 100, 120, 140, 160,180, or 200%.

In some embodiments, the one or more features increase the outputvoltage at the same hydrogen consumption rate when the first continuousstream contacts the anode compared to the equivalent fuel cell lackingthe one or more features.

In some embodiments, the one or more features increase the voltage by atleast 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%.

In some embodiments, the one or more features increase the hydrogenconsumption rate by at most 5, 10, 20, 40, 60, 80, 100, 120, 140, 160,180, or 200%.

In some embodiments, the one or more features continuously purgenitrogen out of the fuel cell.

In some embodiments, the nitrogen is continuously purged out of thefirst channel by the one or more features so that nitrogen accumulationis reduced in the first channel, thereby increasing the hydrogenconsumption rate compared to the equivalent fuel cell lacking the one ormore features.

In some embodiments, the hydrogen consumption rate of the fuel cell whenthe first continuous stream contacts the anode is at least about 10, 20,30, 40, 50, 60, 70, 80, 90, or 99% of the hydrogen in the firstcontinuous stream.

In some embodiments, the hydrogen consumption rate of the fuel cell whenthe first continuous stream contacts the anode is at most about 10, 20,30, 40, 50, 60, 70, 80, 90, or 99% of the hydrogen in the firstcontinuous stream.

In some embodiments, the method further comprises intermittentlyreducing the hydrogen consumption rate to purge out at least one ofhydrogen, nitrogen, or water.

In some embodiments, the method further comprises reducing the hydrogenconsumption rate and directing at least a part of the first continuousstream to the ammonia reformer.

In some embodiments, the method further comprises reducing the hydrogenconsumption rate of the fuel cell to zero and directing at least a partof the first continuous stream to the ammonia reformer.

In some embodiments, the method further comprises flaring the at leastthe part of the first continuous stream directed to the ammonia reformerat one or more combustion exhausts of one or more combustion heaters,wherein the one or more combustion heaters are in operable communicationwith the ammonia reformer for heating the ammonia reformer, and whereinthe one or more combustion heaters are in fluidic communication with thefuel cell to receive the at least the part of the first continuousstream.

In some aspects, the present disclosure provides a method for generatingelectricity using a fuel cell, comprising: reacting, using an ammoniareformer, ammonia to generate a first continuous stream comprisingnitrogen and hydrogen, wherein the ammonia reformer is in fluidcommunication with the fuel cell, the fuel cell comprising: anelectrochemical circuit comprising an anode, a cathode, and anelectrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof; and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and directing thefirst continuous stream into the first channel via the first inlet sothat the hydrogen contacts the anode; directing a second continuousstream comprising oxygen into the second channel via the second inlet sothat the oxygen contacts the cathode; and reacting the hydrogen and theoxygen, using the fuel cell, to generate electrical power; wherein thefuel cell is configured to provide a ratio of an electrical power outputof the fuel cell to a projected surface area of the anode that is atleast about 0.05 W/cm2 when the first continuous stream comprises about25% nitrogen and about 75% hydrogen by moles, and the second continuousstream comprises at least 20% oxygen by moles.

In some embodiments, the ratio is at least about 0.1, 0.15, 0.2, 0.25,0.3, 0.35, or 0.4 W/cm2.

In some embodiments, the ratio is at most about 0.1, 0.15, 0.2, 0.25,0.3, 0.35, or 0.4 W/cm2.

In some embodiments, the ratio is based on the first continuous streamcomprising a hydrogen flow rate of at least about 0.001, 0.01, 0.1, 1,10, 100, 1000, 10000, or 100000 mole per second.

In some embodiments, the ratio is based on the second continuous streamcomprising an oxygen flow rate of at least about 0.0001, 0.001, 0.01,0.1, 1, 10, 100, 1000, 10000, 100000, 1000000 mole per second.

In some embodiments, the ratio is based on the second continuous streamcomprising air.

In some embodiments, the ratio is based on the first continuous streamcomprising the hydrogen and the nitrogen from the ammonia reformer.

In some embodiments, the anode projected surface area comprises thelargest possible surface area of the anode projected onto a flat plane.

In some embodiments, the anode projected surface area comprises asurface area of the largest surface of the anode.

In some aspects, the present disclosure provides a method for generatingelectricity using a fuel cell, comprising: reacting, using an ammoniareformer, ammonia to generate a first continuous stream comprisingnitrogen and hydrogen, wherein the ammonia reformer is in fluidcommunication with a fuel cell, the fuel cell comprising: anelectrochemical circuit comprising an anode, a cathode, and anelectrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof; and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and directing thefirst continuous stream into the first channel via the first inlet sothat the hydrogen contacts the anode; directing a second continuousstream comprising oxygen into the second channel via the second inlet sothat the oxygen contacts the cathode; and reacting the hydrogen and theoxygen, using the fuel cell, to generate electrical power that is atleast 50% of a reference electrical power, wherein the referenceelectrical power is generated using the fuel cell receiving a streamcomprising at least 99% hydrogen by moles into the first inlet, whereinthe electrical power is generated at a same current or a same hydrogenconsumption rate as the reference electrical power.

In some embodiments, the electrical power is at least 60, 70, 80, 90,91, 92, 93, 94, 95, 96, 97, 98, or 99% of the reference electricalpower.

In some embodiments, the electrical power is at most 60, 70, 80, 90, 91,92, 93, 94, 95, 96, 97, 98, or 99% of the reference electrical power.

In some aspects, the present disclosure provides a method for generatingelectricity using a fuel cell, comprising: reacting, using an ammoniareformer, ammonia to generate a first continuous stream comprisingnitrogen and hydrogen, wherein the ammonia reformer is in fluidcommunication with a fuel cell, wherein the fuel cell comprises: anelectrochemical circuit comprising an anode, a cathode, and anelectrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof, wherein the one or morefeatures comprise a depth less than 10 mm; and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and directing thefirst continuous stream into the first channel via the first inlet sothat the hydrogen contacts the anode; directing a second continuousstream comprising oxygen into the second channel via the second inlet sothat the oxygen contacts the cathode; and reacting the hydrogen and theoxygen, using the fuel cell, to generate electrical power.

In some embodiments, the one or more features comprises a depth lessthan 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09,0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01 mm.

In some embodiments, the one or more features comprises a depth greaterthan 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09,0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01 mm.

In some embodiments, the depth is at least 1/32, 1/16, ⅛, ¼, ½, ¾, ⅞,15/16, or 31/32 of the thickness of the first channel.

In some embodiments, the depth is at most 1/32, 1/16, ⅛, ¼, ½, ¾, ⅞,15/16, or 31/32 of the thickness of the first channel.

In some embodiments, the first channel comprises a ratio of a firstprojected surface area of the one or more features to a second projectedsurface area of the first channel that is at least 0.1, 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.8, or 0.9.

In some embodiments, the first channel comprises a ratio of a firstprojected surface area of the one or more features to a second projectedsurface area of the first channel that is at most 0.1, 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.8, or 0.9.

In some embodiments, the one or more features comprise two or morefeatures.

In some embodiments, at least a first segment of a first feature of thetwo or more features is substantially parallel to a second segment of asecond feature of the two or more features.

In some embodiments, at least a first segment of a first feature of thetwo or more features is substantially perpendicular to a second segmentof a second feature of the two or more features.

In some embodiments, at least a first segment of a first feature of thetwo or more features is at an angle to a second segment of a secondfeature of the two or more features, wherein the angle is between 0 and90 degrees, between 15 and 75 degrees, between 0 and 30 degrees, orbetween 30 and 60 degrees.

In some embodiments, the two or more features are connected.

In some embodiments, the two or more features are disconnected.

In some embodiments, the two or more features intersect.

In some embodiments, the one or more features comprise a serpentineshape.

In some embodiments, the one or more features are substantially parallelwith the longest side of the first channel.

In some embodiments, the one or more features are substantially parallelwith the shortest side of the first channel.

In some embodiments, the fuel cell comprises a plurality of channels influid communication with the anode, wherein the plurality of channelscomprise the first channel.

In some embodiments, the plurality of channels comprises a stack oflayers that are adjacent to one another.

In some embodiments, at least one channel in the plurality of channelsdoes not comprise or lacks the one or more features comprising (i) oneor more cuts, (ii) one or more cutouts, (iii) one or more grooves, or(iv) any combination thereof.

In some embodiments, the one or more features are further configured tofacilitate purging of a select material from the anode gas diffusionlayer, wherein the select material comprises one or more of nitrogen,ammonia, water, or one or more impurities.

In some embodiments, the fuel cell further comprises one or more exitports for discharging the select material and unconverted hydrogen fromthe fuel cell.

In some embodiments, the first channel comprises a felt, a foam, acloth, or a paper material.

In some embodiments, the felt, the foam, the cloth, or the papermaterial is a carbon-based material.

In some embodiments, the one or more features extend across at least aportion of the surface of the first channel.

In some embodiments, the electrolyte comprises a proton-exchangemembrane.

In some embodiments, the one or more features are configured to purgenitrogen from the fuel cell while the fuel cell is generatingelectricity.

In some embodiments, a concentration of ammonia in the first continuousstream is at most 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90,80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm.

In some embodiments, a concentration of ammonia in the first continuousstream is at least 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100,90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm.

In some embodiments, the one or more features increase a power densityof the fuel cell by at least 5, 10, 20, 40, 60, 80, 100, 120, 140, 160,180, or 200%.

In some embodiments, a power density of the fuel cell is at least about0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

In some embodiments, a power density of the fuel cell is at most about0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

In some embodiments, the method further comprises outputting a thirdcontinuous stream comprising unconverted hydrogen from the fuel cell.

In some embodiments, the method further comprises directing the thirdcontinuous stream comprising the unconverted hydrogen to the ammoniareformer.

In some embodiments, the method further comprises combusting theunconverted hydrogen to heat the ammonia reformer.

In some embodiments, the method further comprises, using one or more airsupply units, providing at least oxygen to the ammonia reformer tocombust the unconverted hydrogen in the third continuous stream.

In some embodiments, the method further comprises removing water in thethird continuous stream prior to combusting the unconverted hydrogen.

In some embodiments, the method further comprises flaring the thirdcontinuous stream.

In some embodiments, the first continuous stream comprises at most about50, 60, 70, 80, 90, 95, 99, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7,99.8, or 99.9% of hydrogen by moles.

In some embodiments, first continuous stream comprises at least about50, 60, 70, 80, 90, 95, 99, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7,99.8, or 99.9% of hydrogen by moles.

In some embodiments, an absolute pressure of the first continuous streamis at least about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or40 bar.

In some embodiments, an absolute pressure of the first continuous streamis at most about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or40 bar.

In some embodiments, the method further comprises maintaining theabsolute pressure of the first continuous stream within a tolerance of1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 150, 200, 300, 400,500, or 1000% of the absolute pressure.

In some embodiments, the method further comprises modulating theabsolute pressure of the first continuous stream using one or more flowregulators, pressure regulators, control units, or any combinationthereof.

In some embodiments, the one or more flow regulators, pressureregulators, control units, or any combination thereof are positionedupstream or downstream of the fuel cell.

In some embodiments, the method further comprises modulating a flow rateof the third continuous stream using one or more flow regulators,pressure regulators, control units, or any combination thereof.

In some embodiments, the one or more flow regulators, pressureregulators, control units, or any combination thereof are positionedupstream or downstream of the fuel cell.

In some embodiments, the one or more flow regulators, pressureregulators, control units, or any combination thereof are positioneddownstream of the fuel cell to prevent a back flow of the unconvertedhydrogen.

In some embodiments, the method further comprises using the generatedelectrical power to power one or more electric devices.

In some embodiments, the method further comprises using the generatedelectrical power to power one or more electrical grids.

In some embodiments, the fuel cell comprises a plurality of fuel cells,and the ammonia reformer provides a plurality of streams comprisinghydrogen and nitrogen to the plurality of the fuel cells.

In some embodiments, the method further comprises directing unconvertedhydrogen from the plurality of fuel cells to the at least one ammoniareformer or reactor for combustion heating.

In some embodiments, at least one fuel cell of the plurality of fuelcells outputs a different electrical power than other fuel cells of theplurality of fuel cells.

In some embodiments, at least one fuel cell of the plurality of fuelcells is configured to reduce an electrical power output.

In some embodiments, the method further comprises modulating the flowrates of the plurality of streams using one or more flow regulators,pressure regulators, control units, or any combination thereof.

In some embodiments, at least one fuel cell of the plurality of the fuelcells receives a stream of the plurality of streams, the streamcomprising a flow rate that is different from the flow rates of otherstreams of the plurality of streams.

In some embodiments, each of the plurality of the fuel cells receivesone of the plurality of streams at a flow rate that is about the same asor within a selected tolerance of other flow rates of others of theplurality of streams.

In some embodiments, the selected tolerance is about 10, 20, 30, 40, 50,60, 70, 80, 90, or 100%.

In some embodiments, the plurality of fuel cells comprises at least onefuel cell that is different in size, power output, hydrogen consumptionrate, power density, or operating temperature from the other fuel cells.

In some aspects, the present disclosure provides a system comprising: anammonia reformer configured to react ammonia to generate a firstcontinuous stream comprising nitrogen and hydrogen; a fuel cell in fluidcommunication with the ammonia reformer, wherein the fuel cellcomprises: an electrochemical circuit comprising an anode, a cathode,and an electrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features configured to (i) increase a hydrogenconsumption rate, or (ii) increase an output voltage at the samehydrogen consumption rate, when the first continuous stream contacts theanode compared to an equivalent fuel cell lacking the one or morefeatures, wherein the one or more features comprise (i) one or morecuts, (ii) one or more cutouts, (iii) one or more grooves, or (iv) anycombination thereof, and a second channel comprising a second inlet anda second outlet, wherein the second channel is in fluid communicationwith the cathode; and a controller comprising at least one processorconfigured to perform executable instructions, wherein instructionsexecutable by the controller are configured to: react the ammonia, usingthe ammonia reformer, to generate the first continuous stream comprisinghydrogen and nitrogen; direct a second continuous stream comprisingoxygen to the cathode of the fuel cell; and direct the first continuousstream to the anode of the fuel cell to react the hydrogen and oxygen togenerate electricity.

In some embodiments, the one or more features increase a hydrogenconsumption rate of the fuel cell when the first continuous streamcontacts the anode compared to the equivalent fuel cell lacking the oneor more features.

In some embodiments, the one or more features increase the hydrogenconsumption rate by at least 20, 40, 60, 80, 100, 120, 140, 160, 180, or200%.

In some embodiments, the one or more features increase the hydrogenconsumption rate by at most 20, 40, 60, 80, 100, 120, 140, 160, 180, or200%.

In some embodiments, the one or more features increase the outputvoltage at the same hydrogen consumption rate when the first continuousstream contacts the anode compared to the equivalent fuel cell lackingthe one or more features.

In some embodiments, the one or more features increase the outputvoltage at the same hydrogen consumption rate by at least 20, 40, 60,80, 100, 120, 140, 160, 180, or 200%.

In some embodiments, the one or more features increase the hydrogenconsumption rate by at most 20, 40, 60, 80, 100, 120, 140, 160, 180, or200%.

In some embodiments, the one or more features continuously purgenitrogen out of the fuel cell.

In some embodiments, the nitrogen is continuously directed out of thefirst channel by the one or more features so that nitrogen accumulationis reduced in the first channel, thereby increasing the hydrogenconsumption rate compared to the equivalent fuel cell lacking the one ormore features.

In some embodiments, the hydrogen consumption rate of the fuel cell whencontacting the first continuous stream with the anode is at least about10, 20, 30, 40, 50, 60, 70, 80, 90, or 99% of the hydrogen in the firstcontinuous stream.

In some embodiments, the hydrogen consumption rate of the fuel cell whencontacting the first continuous stream with the anode is at most about10, 20, 30, 40, 50, 60, 70, 80, 90, or 99% of the hydrogen in the firstcontinuous stream.

In some embodiments, the instructions executable by the controller arefurther configured to intermittently reduce the hydrogen consumptionrate to purge out at least one of hydrogen, nitrogen, or water.

In some embodiments, the instructions executable by the controller arefurther configured to reduce the hydrogen consumption rate and direct atleast a part of the first continuous stream to the ammonia reformer.

In some embodiments, the instructions executable by the controller arefurther configured to reduce the hydrogen consumption rate of the fuelcell to zero and direct at least a part of the first continuous streamto the ammonia reformer.

In some embodiments, the instructions executable by the controller arefurther configured to flare the at least the part of the firstcontinuous stream directed to the ammonia reformer at one or morecombustion exhausts of one or more combustion heaters, wherein the oneor more combustion heaters are in operable communication with theammonia reformer for heating the ammonia reformer, and wherein the oneor more combustion heaters are in fluidic communication with the fuel toreceive the at least the part of the first continuous stream.

In some aspects, the present disclosure provides a fuel cell comprising:an electrochemical circuit comprising an anode, a cathode, and anelectrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof, and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; wherein the fuelcell is configured to provide a ratio of an electrical power output ofthe fuel cell to a projected surface area of the anode that is at leastabout 0.05 W/cm2 when the first inlet is supplied with a firstcontinuous stream comprising about 25% nitrogen and about 75% hydrogenby moles, and the second inlet is supplied with a second continuousstream comprising at least 20% oxygen by moles.

In some embodiments, the ratio is at least about 0.1, 0.15, 0.2, 0.25,0.3, 0.35, or 0.4 W/cm2.

In some embodiments, the ratio is at most about 0.1, 0.15, 0.2, 0.25,0.3, 0.35, or 0.4 W/cm2.

In some embodiments, the ratio is based on the first continuous streamcomprising a hydrogen flow rate of at least about 0.001, 0.01, 0.1, 1,10, 100, 1000, 10000, 100000 mole per second.

In some embodiments, the ratio is based on the second continuous streamcomprising an oxygen flow rate of at least about 0.0001, 0.001, 0.01,0.1, 1, 10, 100, 1000, 10000, 100000, 1000000 mole per second.

In some embodiments, the ratio is based on the second continuous streamcomprising air.

In some embodiments, the ratio is based on the first continuous streamcomprising the hydrogen and the nitrogen from the ammonia reformer.

In some embodiments, the projected surface area of the anode comprisesthe largest possible surface area of the anode projected onto a flatplane.

In some embodiments, the projected surface area of the anode comprises asurface area of the largest surface of the anode.

In some aspects, the present disclosure provides a fuel cell comprising:an electrochemical circuit comprising an anode, a cathode, and anelectrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features; and a second channel comprising a secondinlet and a second outlet, wherein the second channel is in fluidcommunication with the cathode; wherein the fuel cell is in fluidcommunication with an ammonia reformer configured to provide nitrogenand hydrogen to the fuel cell; and wherein the fuel cell is configuredto generate an electrical power at least 80% of a reference electricalpower, wherein the reference electrical power is generated using thefuel cell receiving a continuous stream comprising at least 99% hydrogenby moles into the first inlet, wherein the electrical power is generatedat a same current or a same hydrogen consumption rate as the referenceelectrical power.

In some embodiments, the electrical power is at least 60, 70, 80, 90,91, 92, 93, 94, 95, 96, 97, 98, or 99% of the reference electricalpower.

In some embodiments, the electrical power is at most 60, 70, 80, 90, 91,92, 93, 94, 95, 96, 97, 98, or 99% of the reference electrical power.

In some aspects, the present disclosure provides a system comprising: anammonia reformer; a fuel cell in fluid communication with the ammoniareformer, wherein the fuel cell comprises: an electrochemical circuitcomprising an anode, a cathode, and an electrolyte between the anode andthe cathode; a first channel comprising a first inlet and a firstoutlet, wherein the first channel is in fluid communication with theanode, wherein the first channel comprises one or more features, whereinthe one or more features comprise (i) one or more cuts, (ii) one or morecutouts, (iii) one or more grooves, or (iv) any combination thereof,wherein the one or more features comprise a depth less than 10 mm; and asecond channel comprising a second inlet and a second outlet, whereinthe second channel is in fluid communication with the cathode; and acontroller comprising at least one processor configured to performexecutable instructions, wherein instructions executable by thecontroller are configured to: direct ammonia to the ammonia reformer togenerate a first continuous stream comprising hydrogen and nitrogen;direct a second continuous stream comprising oxygen to the cathode ofthe fuel cell; and direct the first continuous stream to the anode ofthe fuel cell to react the hydrogen and oxygen to generate electricity.

In some embodiments, the one or more features comprises a depth lessthan 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09,0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01 mm.

In some embodiments, the one or more features comprises a depth greaterthan 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09,0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01 mm.

In some embodiments, the depth is at least 1/32, 1/16, ⅛, ¼, or ½ of thethickness of the first channel.

In some embodiments, the depth is at most 1/32, 1/16, ⅛, ¼, or ½ of thethickness of the first channel.

In some embodiments, a ratio of a first projected surface area of theone or more features to a second projected surface area of the firstchannel is at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

In some embodiments, a ratio of a first projected surface area of theone or more features to a second projected surface area of the firstchannel is at most 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

In some embodiments, the ammonia reformer generates the first continuousstream additionally comprising at most 1000, 900, 800, 700, 600, 500,400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5,4, 3, 2, or 1 ppm of ammonia.

In some embodiments, the ammonia reformer generates the first continuousstream additionally comprising at least 1000, 900, 800, 700, 600, 500,400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5,4, 3, 2, or 1 ppm of ammonia.

In some embodiments, the one or more features comprises two or morefeatures.

In some embodiments, at least a first segment of a first feature of thetwo or more features is substantially parallel to a second segment of asecond feature of the two or more features.

In some embodiments, at least a first segment of a first feature of thetwo or more features is substantially perpendicular to a second segmentof a second feature of the two or more features.

In some embodiments, at least a first segment of a first feature of thetwo or more features is at an angle to a second segment of a secondfeature of the two or more features, wherein the angle is between 0 and90 degrees, between 15 and 75 degrees, between 0 and 30 degrees, orbetween 30 and 60 degrees.

In some embodiments, the two or more features are connected.

In some embodiments, the two or more features are disconnected.

In some embodiments, the two or more features intersect.

In some embodiments, the one or more features are fully enclosed by thefirst channel.

In some embodiments, the one or more features are partially enclosed bythe first channel.

In some embodiments, the one or more features comprise a serpentineshape.

In some embodiments, the one or more features are substantially parallelwith the longest side of the first channel.

In some embodiments, the one or more features are substantially parallelwith the shortest side of the first channel.

In some embodiments, the fuel cell comprises a plurality of channels influid communication with the anode, wherein the plurality of channelscomprises the first channel.

In some embodiments, the plurality of channels comprises a stack oflayers that are adjacent to one another.

In some embodiments, at least one channel in the plurality of channelsdoes not comprise or lacks the one or more features comprising (i) oneor more cuts, (ii) one or more cutouts, (iii) one or more grooves, or(iv) any combination thereof.

In some embodiments, the one or more features are further configured tofacilitate purging of a select material from the anode gas diffusionlayer, wherein the select material comprises one or more of nitrogen,ammonia, water, or one or more impurities.

In some embodiments, the fuel cell further comprises one or more exitports for discharging the select material and unconverted hydrogen fromthe fuel cell.

In some embodiments, the first channel comprises a felt, a foam, acloth, or a paper material.

In some embodiments, the felt, the foam, the cloth, or the papermaterial is a carbon-based material.

In some embodiments, the one or more features extend across at least aportion of the surface of the first channel.

In some embodiments, the electrolyte comprises a proton-exchangemembrane.

In some embodiments, the fuel cell is configured to allow purging ofnitrogen from the fuel cell while the fuel cell is generatingelectricity.

In some embodiments, the first channel is supplied with a streamcomprising a concentration of ammonia of at most 1000, 900, 800, 700,600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8,7, 6, 5, 4, 3, 2, or 1 ppm.

In some embodiments, the first channel is supplied with a streamcomprising a concentration of ammonia of at least 1000, 900, 800, 700,600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8,7, 6, 5, 4, 3, 2, or 1 ppm.

In some embodiments, the one or more features increase a power densityof the fuel cell by at least 5, 10, 20, 40, 60, 80, 100, 120, 140, 160,180, or 200%.

In some embodiments, a power density of the fuel cell is at least about0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

In some embodiments, a power density of the fuel cell is at most about0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

In some embodiments, the system or the fuel cell further comprises oneor more combustion heaters for combusting an exit stream output by thefuel cell to heat the ammonia reformer, wherein the exit streamcomprises unconverted hydrogen.

In some embodiments, the system or the fuel cell further comprises oneor more air supply units for providing at least oxygen to the one ormore combustion heaters.

In some embodiments, the system or the fuel cell further comprises oneor more dehydrators for removing water in the exit stream in prior tocombusting the unconverted hydrogen.

In some embodiments, the system is configured to flare the unconvertedhydrogen at a combustion exhaust of the one or more combustion heaters.

In some embodiments, the system or the fuel cell further comprises g oneor more flow regulators, pressure regulators, control units, or anycombination thereof for modulating an absolute pressure of an inputstream or an output stream of the fuel cell.

In some embodiments, the one or more flow regulators, pressureregulators, control units, or any combination thereof are positionedupstream or downstream of the fuel cell.

In some embodiments, the one or more flow regulators, pressureregulators, control units, or any combination thereof are positioneddownstream of the fuel cell to reduce or prevent a back flow of theunconverted hydrogen.

In some embodiments, the system or the fuel cell further comprises anelectrical load connected to the electrochemical circuit.

In some embodiments, the electrical load comprises one or more electricdevices.

In some embodiments, the electrical load comprises one or moreelectrical grids.

In some embodiments, the electrical load comprises an engine or a motor.

In some embodiments, the fuel cell comprises a plurality of fuel cellsin operable communication with the ammonia reformer, the ammoniareformer configured to provide a plurality of streams comprisinghydrogen and nitrogen to the plurality of the fuel cells.

In some embodiments, the system is configured to direct unconvertedhydrogen from the plurality of fuel cells to one or more combustors inthermal communication with the ammonia reformer.

In some embodiments, at least one fuel cell of the plurality of fuelcells comprises a different electrical power output than other fuelcells of the plurality of fuel cells.

In some embodiments, at least one fuel cell of the plurality of fuelcells is configured to reduce an electrical power output.

In some embodiments, one or more ammonia reformers in fluidcommunication with the plurality of fuel cells provide to at least onefuel cell of the plurality of the fuel cells a stream that comprises aflow rate that is different from the flow rate of another streamprovided to another fuel cell.

In some embodiments, one or more ammonia reformers in fluidcommunication with the plurality of fuel cells are configured to providea plurality of streams to the plurality of fuel cells, wherein the flowrates of the plurality of streams is about the same as or within aselected tolerance of other flow rates of others of the plurality ofstreams.

In some embodiments, the selected tolerance is about 10, 20, 30, 40, 50,60, 70, 80, 90, or 100%.

In some embodiments, the plurality of fuel cells comprises at least onefuel cell that is different in size, power output, hydrogen consumptionrate, power density, or operating temperature from the other fuel cells.

In some aspects, the present disclosure provides a fuel cell,comprising: an anode; a cathode; and a membrane between the anode andthe cathode, wherein the anode comprises an anode gas diffusion layerwith one or more channels for directing a source material comprisinghydrogen and nitrogen to the anode for processing of the source materialto generate an electrical current, wherein the one or more channelscomprise one or more features comprising (i) one or more cuts, (ii) oneor more cutouts, or (iii) one or more grooves configured to enhancediffusion and transport of the source material through the anode gasdiffusion layer, and wherein the one or more features are configured todirect a flow of nitrogen from the anode gas diffusion layer to out ofthe fuel cell so that nitrogen does not accumulate in the anode gasdiffusion layer.

In some embodiments, the one or more features comprise two or morefeatures.

In some embodiments, the one or more features are further configured tofacilitate purging of a select material from the anode gas diffusionlayer, wherein the select material comprises one or more of nitrogen,ammonia, water, or one or more impurities.

In some embodiments, the fuel cell further comprises one or more exitports for discharging the select material and unconverted hydrogen fromthe fuel cell.

In some embodiments, the processing of the source material comprises adissociation of one or more hydrogen molecules of the source materialinto one or more protons and one or more electrons.

In some embodiments, the anode gas diffusion layer comprises a felt, afoam, a cloth, or a paper material.

In some embodiments, the felt, the foam, the cloth, or the papermaterial is a carbon-based material.

In some embodiments, the one or more features extend across at least aportion of the surface of the one or more channels.

In some embodiments, the two or more features are parallel to eachother.

In some embodiments, the two or more features are perpendicular to eachother.

In some embodiments, the two or more features are disposed at an anglerelative to each other, wherein the angle ranges from 0 degrees to 90degrees.

In some embodiments, the two or more features intersect with each other.

In some embodiments, the two or more features do not intersect.

In some embodiments, the anode gas diffusion layer comprises a pluralityof layers.

In some embodiments, at least one layer of the plurality of layerscomprises the one or more channels comprising the one or more features.

In some embodiments, the plurality of layers comprises a first layercomprising a first set of features and a second layer comprising asecond set of features.

In some embodiments, the first set of features and the second set offeatures comprise a same or similar set of features.

In some embodiments, the first set of features and the second set offeatures comprise different sets of features having different shapes,dimensions, positions, or orientations.

In some embodiments, the first set of features and the second set offeatures overlap or partially overlap.

In some embodiments, the first set of features and the second set offeatures do not overlap.

In some embodiments, at least one feature of the one or more featureshas a depth ranging from about 0.01 millimeter (mm) to about 10 mm.

In some aspects, the present disclosure provides a fuel cell system,comprising: a plurality of fuel cells comprising a fuel cell disclosedherein, at least one ammonia reformer or reactor in fluid communicationwith the plurality of fuel cells, wherein the at least one ammoniareformer or reactor is configured to (i) generate the source materialand (ii) provide the source material to the fuel cell.

In some embodiments, the plurality of fuel cells are arranged (i)adjacent to each other in a lateral configuration or (ii) on top of eachother in a stacked configuration.

In some embodiments, the plurality of fuel cells comprises at least oneproton-exchange membrane fuel cell (PEMFC).

In some aspects, the present disclosure provides a fuel cell systemcomprising a fuel cell disclosed herein, wherein the fuel cell systemcomprises a controller configured to operate the fuel cell to allowpurging of nitrogen from the fuel cell while the fuel cell is generatingelectricity.

In some embodiments, the fuel cell system further comprises a controllerconfigured to operate the fuel cell to allow purging of nitrogen fromthe fuel cell while the fuel cell is generating electricity.

In some embodiments, at least one feature of the one or more featureshas a depth ranging from about 0.01 millimeter (mm) to about 10 mm.

In some embodiments, the fuel cell system further comprises one or moreinlet ports configured to receive the source material, wherein ammoniaconcentration in the source material is less than 1 ppm.

In some embodiments, the fuel cell system further comprises one or moreexit ports configured to direct unconverted hydrogen from the pluralityof fuel cells to the at least one ammonia reformer or reactor, whereinthe unconverted hydrogen is combusted to heat the ammonia reformer orreactor.

Another aspect of the present disclosure provides a non-transitorycomputer readable medium comprising machine executable code that, uponexecution by one or more computer processors, implements any of themethods above or elsewhere herein.

Another aspect of the present disclosure provides a system comprisingone or more computer processors and computer memory coupled thereto. Thecomputer memory comprises machine executable code that, upon executionby the one or more computer processors, implements any of the methodsabove or elsewhere herein.

Additional aspects and advantages of the present disclosure will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only illustrative embodiments of thepresent disclosure are shown and described. As will be realized, thepresent disclosure is capable of other and different embodiments, andits several details are capable of modifications in various obviousrespects, all without departing from the disclosure. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.To the extent publications and patents or patent applicationsincorporated by reference contradict the disclosure contained in thespecification, the specification is intended to supersede and/or takeprecedence over any such contradictory material.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings (also “Figure” and “FIG.” herein), of which:

FIG. 1 schematically illustrates a fuel cell system, in accordance withsome embodiments.

FIGS. 2A-2B schematically illustrate H₂/N₂ diffusion in a gas diffusionlayer of a conventional fuel cell.

FIG. 3 schematically illustrates performance improvements for anodechannels comprising one or more cuts, in accordance with someembodiments.

FIG. 4 schematically illustrates performance improvements for anodechannels comprising one or more cutouts, in accordance with someembodiments.

FIG. 5 schematically illustrates performance improvements for anodechannels comprising various multilayer designs, in accordance with someembodiments.

FIG. 6 schematically illustrates a stack of fuel cells comprising aplurality of fuel cells, in accordance with some embodiments.

FIG. 7 schematically illustrates durability testing results for a stackof fuel cells with a multi-layer gas diffusion layer design whennitrogen is present in a hydrogen gas mixture (3:1 hydrogen and nitrogenvolume ratio), in accordance with some embodiments.

FIG. 8 schematically illustrates durability testing results for a stackof fuel cells with a multi-layer gas diffusion layer design with ahydrogen and nitrogen gas mixture stream produced from an ammoniareforming process, in accordance with some embodiments.

FIG. 9 schematically illustrates a system for processing a sourcematerial comprising hydrogen and nitrogen, in accordance with someembodiments.

FIG. 10 schematically illustrates a process for feeding reformate gas toa fuel cell, in accordance with some embodiments.

FIG. 11 schematically illustrates various examples of cut configurationsthat may be utilized for an anode channel of a fuel cell, in accordancewith some embodiments.

FIG. 12 schematically illustrates various examples of cutoutconfigurations that may be utilized for an anode channel of a fuel cell,in accordance with some embodiments.

FIG. 13 schematically illustrates various examples of multi-layer anodechannel designs, in accordance with some embodiments.

FIG. 14 schematically illustrates a computer system that is programmedor otherwise configured to implement methods provided herein.

FIG. 15 shows energy density of ammonia compared with other fuels, inaccordance with some embodiments.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and describedherein, it will be obvious to those skilled in the art that suchembodiments are provided by way of example only. Numerous variations,changes, and substitutions may occur to those skilled in the art withoutdeparting from the invention. It should be understood that variousalternatives to the embodiments of the invention described herein may beemployed.

Whenever the term “at least,” “greater than,” or “greater than or equalto” precedes the first numerical value in a series of two or morenumerical values, the term “at least,” “greater than” or “greater thanor equal to” applies to each of the numerical values in that series ofnumerical values. For example, greater than or equal to 1, 2, or 3 isequivalent to greater than or equal to 1, greater than or equal to 2, orgreater than or equal to 3.

Whenever the term “no more than,” “less than,” or “less than or equalto” precedes the first numerical value in a series of two or morenumerical values, the term “no more than,” “less than,” or “less than orequal to” applies to each of the numerical values in that series ofnumerical values. For example, less than or equal to 3, 2, or 1 isequivalent to less than or equal to 3, less than or equal to 2, or lessthan or equal to 1.

The term “real time” or “real-time,” as used interchangeably herein,generally refers to an event (e.g., an operation, a process, a method, atechnique, a computation, a calculation, an analysis, a visualization,an optimization, etc.) that is performed using recently obtained (e.g.,collected or received) data. In some cases, a real time event may beperformed almost immediately or within a short enough time span, such aswithin at least 0.0001 millisecond (ms), 0.0005 ms, 0.001 ms, 0.005 ms,0.01 ms, 0.05 ms, 0.1 ms, 0.5 ms, 1 ms, 5 ms, 0.01 seconds, 0.05seconds, 0.1 seconds, 0.5 seconds, 1 second, or more. In some cases, areal time event may be performed almost immediately or within a shortenough time span, such as within at most 1 second, 0.5 seconds, 0.1seconds, 0.05 seconds, 0.01 seconds, 5 ms, 1 ms, 0.5 ms, 0.1 ms, 0.05ms, 0.01 ms, 0.005 ms, 0.001 ms, 0.0005 ms, 0.0001 ms, or less.

The term “at least one of A and B” and “at least one of A or B” may beunderstood to mean only A, only B, or both A and B. The term “A and/orB” may be understood to mean only A, only B, or both A and B.

Fuel Cell

In an aspect, the present disclosure provides one or more fuel cells forprocessing a source material. FIG. 1 schematically illustrates a fuelcell, in accordance with some embodiments. A fuel cell can comprise anelectrochemical circuit comprising an anode (101), a cathode (103), andan electrolyte (102) between the anode and the cathode. Theelectrochemical circuit can comprise an electrical load (104) configuredto receive electrical energy generated by the fuel cell. The fuel cellcan comprise a first channel (105; “the anode channel”) comprising afirst inlet (106) and a first outlet (107), wherein the first channel isin fluid communication with the anode. The anode channel can comprise agas diffusion layer (GDL) for the anode, which can be referred to as theanode diffusion layer. The fuel cell can comprise a second channel (108;“the cathode channel”) comprising a second inlet (109) and a secondoutlet (110), wherein the second channel is in fluid communication withthe cathode. The cathode channel can comprise a GDL for the cathode,which can be referred to as the cathode diffusion layer.

The source material (111) can comprise hydrogen. The source material canbe provided to the first inlet (106), such that the source materialcontacts the anode. The source material may diffuse to the anodecatalyst where it dissociates into protons and electrons. Using theanode, the fuel cell can carry out a first half reaction comprisingH₂→2H⁺+2e⁻. The protons (H⁺) may be conducted through the electrolyte tothe cathode, while the electrons (e⁻) are directed to travel along anexternal circuit through the electrical load to the cathode. A streamcomprising oxidizing material (113; e.g., oxygen) can be provided to thesecond inlet (109), such that the stream contacts the cathode. Using thecathode, the fuel cell can carry out a second half reaction comprising2H⁺+2e⁻+½O₂→H₂O. Oxygen can react with the protons and the electrons(both of which have traveled from the anode through the electrolyte andthe external circuit, respectively) to form a byproduct (e.g., water).As a whole, the fuel cell can carry out an electrochemical reactioncomprising 2H₂+O₂→2H₂O. The standard potential of the electrochemicalreaction is about 1.23 Volts. The output voltage of the fuel cell can belower than the standard potential, due to electrical potential lossesduring operation of the fuel cell (e.g., due to kinetic losses, Ohmiclosses, and/or mass transfer losses).

The source material (111) can be processed by the one or more fuel cellsto generate energy (e.g., electrical energy). In some embodiments, thesource material may be provided or be received from one or morecomponents or subcomponents of an ammonia reforming system (112; e.g., asystem for cracking or decomposing ammonia into hydrogen and nitrogen).The source material from the ammonia reforming system can comprise, forexample, a storage (114) for storing fuel (e.g., hydrogen, nitrogen,and/or ammonia) and optionally a reactor (115) for reacting the fuel togenerate hydrogen and nitrogen (e.g., in a volume ratio of H₂ to N₂ ofabout 3:1).

In some cases, processing a source material comprising hydrogen andnitrogen can reduce the electrical power of a fuel cell, compared toprocessing high purity hydrogen (e.g., greater than 99% purity). FIG. 2Ashows the current-voltage characteristic plot of a fuel cell when thefuel cell is processing a source material comprising high purityhydrogen (e.g., about 99.999% purity hydrogen by volume) versus a sourcematerial comprising a mixture of about 75% hydrogen and about 25%nitrogen. The fuel cell receiving the mixture of hydrogen and nitrogenshowed significantly lower electrical energy generation. FIG. 2Bschematically illustrates H₂ versus H₂/N₂ diffusion and transport in aGDL of an example fuel cell. In cases where the GDL is used fordiffusion and transport of a source material comprising mostly hydrogen,the hydrogen can flow from an inlet of the GDL to an outlet of the GDL.As the hydrogen flows through the GDL, it may also diffuse to theproton-exchange membrane (PEM) where the dissociation or transfer ofions takes place. Without being bound to a particular theory, in caseswhere the GDL is used for transport of a source material comprising bothhydrogen and nitrogen (e.g., a hydrogen/nitrogen mixture), the transportof hydrogen to the PEM may be restricted, in part due to the buildup oraccumulation of nitrogen in the GDL (the nitrogen may dilute thestream). This accumulation can lead to greater electrical potentiallosses associated with mass transfer of the hydrogen in the GDL. In somecases, this accumulation can lead to non-uniform dispersion of hydrogenthrough the GDL (e.g., some portions of the GDL may receive lesshydrogen compared to other portions of the GDL). In some cases, thisaccumulation can lead to non-uniform dispersion of hydrogen to the anode(e.g., some portion of the anode may receive less hydrogen compared toother portions of the anode). In some cases, this accumulation can leadto insufficient hydrogen ion transport through the PEM. Thisaccumulation can lead to reduced fuel cell performance and/or fuel cellstarvation.

In some embodiments, an anode channel can comprise one or more featuresconfigured to improve processing a source material comprising hydrogenand nitrogen by the fuel cell. In some embodiments, the one or morefeatures can comprise one or more cuts, one or more cutouts, and/or oneor more grooves. The one or more features can be configured tocontinuously purge nitrogen out of the fuel cell. Reducing the nitrogenaccumulation in at least part of the anode can increase a hydrogenconsumption rate of the fuel cell, increase an output voltage of thefuel cell, or both. In some cases, reducing the nitrogen accumulation inat least a part adjacent to the anode can increase a hydrogenconsumption rate of the fuel cell, increase an output voltage of thefuel cell, or both. The one or more features can be configured to purgenitrogen from the fuel cell while the fuel cell is generatingelectricity. The anode channel comprising the one or more features cancomprise a GDL comprising the one or more features.

FIG. 3 schematically illustrates performance improvements for anodechannels comprising one or more cuts. In instances where a mixture ofhydrogen and nitrogen (e.g., about 3:1 volume ratio) is provided to afuel cell for processing to generate electrical energy, the outputvoltage of a fuel cell comprising one or more cut configurations in theanode channel may be significantly greater than that of a fuel cellwithout any cuts in the anode channels. In some cases, a fuel cellcomprising a higher density of cuts on the surface of the anode channelmay exhibit better performance (e.g., a higher output voltage whenprocessing a hydrogen/nitrogen mixture to generate electrical energy)compared to a fuel cell with a lower density of cuts on the surface ofthe anode channel.

FIG. 4 schematically illustrates performance improvements for anodechannels comprising one or more cutouts. In instances where a mixture ofhydrogen and nitrogen (about 3:1 volume ratio) is provided to a fuelcell for processing to generate electrical energy, the output voltage ofa fuel cell comprising one or more cutout configurations in the anodechannel may be significantly greater than that of a fuel cell withoutany cutouts in the anode channels. In some cases, a fuel cell comprisinga higher density of cutouts on the surface of the anode channel mayexhibit better performance (e.g., a higher output voltage whenprocessing a hydrogen/nitrogen mixture to generate electrical energy)compared to a fuel cell with a lower density of cutouts on the surfaceof the anode channel. In some cases, a fuel cell comprising a density ofcutouts on the surface of the anode channel that is too high may reducethe performance compared to a fuel cell with a lower density of cutoutson the surface of the anode channel.

FIG. 5 schematically illustrates performance improvements for anodechannels comprising various multilayer anode channel designs. Themultilayer anode channel designs can comprise a plurality of layerscomprising one or more cuts, cutouts, grooves, or any combinationthereof. In instances where a mixture of hydrogen and nitrogen isprovided to a fuel cell for processing to generate electrical energy,the output voltage of a fuel cell comprising a multilayer anode channeldesign may be significantly greater than that of a fuel cell without amultilayer anode channel design.

As shown in FIG. 3 , FIG. 4 , and FIG. 5 , the one or more features ofthe anode channels can allow generation electrical power that is atleast 50% of a reference electrical power, wherein the referenceelectrical power is generated using the fuel cell receiving a streamcomprising at least 99% hydrogen by moles into the first inlet. Forinstance, the “Cut 2” design shown in FIG. 3 exhibits about 60% ofvoltage of the reference electrical power at a current of about 20 Amps.Some designs show nearly 100% of the voltage of the reference electricalpower, e.g., “Design 1” shown in FIG. 5 . The electrical power and thereference electrical power of the fuel cell can be generated at a samecurrent or a same hydrogen consumption rate. In some cases, theelectrical power is at least 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97,98, or 99% of the reference electrical power. In some cases, theelectrical power is at most 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97,98, or 99% of the reference electrical power.

The one or more features can increase the hydrogen consumption rate ofthe fuel cell. The increase in the hydrogen consumption rate of the fuelcell may be in comparison to an equivalent fuel cell without the one ormore features. In some cases, the one or more features increase thehydrogen consumption rate by at least 5, 10, 20, 40, 60, 80, 100, 120,140, 160, 180, or 200%. In some cases, the one or more features increasethe hydrogen consumption rate by at most 5, 10, 20, 40, 60, 80, 100,120, 140, 160, 180, or 200%. In some cases, the hydrogen consumptionrate can be at least about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 99% ofthe hydrogen provided to the fuel cell. In some cases, the hydrogenconsumption rate can be at most about 10, 20, 30, 40, 50, 60, 70, 80,90, or 99% of the hydrogen provided to the fuel cell.

In some cases, the hydrogen consumption rate of the fuel cell can beadjusted to maintain an autothermal reforming process of the ammoniareformer. An autothermal reforming process may be construed as a processin which the ammonia reforming process of the ammonia reformer generatesa net positive production of hydrogen by combusting or consuming atleast part of the hydrogen produced by the ammonia reformer. In somecases, an autothermal reforming process of the ammonia reformer ismaintained by combusting at least part of hydrogen provided to the fuelcell that is not consumed by the fuel cell (e.g., unconverted hydrogen).For example, the unconverted hydrogen may be directed to one or morecombustion heaters of the ammonia reformer, and combusted in the one ormore combustion heaters to heat the ammonia reformer. In some cases, anautothermal reforming process of the ammonia reformer is maintained bycombusting at least part of hydrogen provided to the fuel cell that isnot consumed by the fuel cell, and additionally by electrical heatingprovided by at least part of the electricity generated from the fuelcell. In some cases, an autothermal reforming process of the ammoniareformer is maintained by combusting at least part of the hydrogenproduced by the ammonia reformer, and additionally by electrical heatingprovided by at least part of the electricity generated from the fuelcell.

The hydrogen consumption rate may be adjusted by modulating a load powerof the fuel cell (e.g., the power required by a device in electricalcommunication with the fuel cell). In some cases, the hydrogenconsumption rate of the fuel cell is about 20% to 40% of the hydrogenprovided to the fuel cell to maintain the autothermal reforming processof the ammonia reformer. In some cases, the hydrogen consumption rate isabout 30% to 50% of the hydrogen provided to the fuel cell to maintainthe autothermal reforming process of the ammonia reformer. In somecases, the hydrogen consumption rate is about 40% to 60% of the hydrogenprovided to the fuel cell to maintain the autothermal reforming processof the ammonia reformer. In some cases, the hydrogen consumption rate isabout 50% to 70% of the hydrogen provided to the fuel cell to maintainthe autothermal reforming process of the ammonia reformer. In somecases, the hydrogen consumption rate is about 60% to 80% of the hydrogenprovided to the fuel cell to maintain the autothermal reforming processof the ammonia reformer. In some cases, the hydrogen consumption rate isabout 70% to 90% of the hydrogen provided to the fuel cell to maintainthe autothermal reforming process of the ammonia reformer. In somecases, the hydrogen consumption rate is about 55% to 75% of the hydrogenprovided to the fuel cell to maintain the autothermal reforming processof the ammonia reformer. In some cases, the hydrogen consumption rate isat least about 20, 30, 40, 50, 60, 70, 80, or 90% to maintain theautothermal reforming process of the ammonia reformer. In some cases,the hydrogen consumption rate is at most about 20, 30, 40, 50, 60, 70,80, or 90% to maintain the autothermal reforming process of the ammoniareformer.

In some cases, the hydrogen consumption rate is maintained within aselected tolerance of a target hydrogen consumption rate to maintain theautothermal reforming process of the ammonia reformer. For example, fora target hydrogen consumption rate of 50% with a selected tolerance of10%, the hydrogen consumption rate may be maintained in the range offrom 45% to 55%. In some cases, the selected tolerance of a targethydrogen consumption rate is at least about 1%, 5%, 10%, 15%, 20%, 30%,40%, 50%, 60%, 70%, 80%, 90%, or 100% of the target consumption rate. Insome cases, the selected tolerance of a target hydrogen consumption rateis at most about 1%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%,90%, or 100% of the target consumption rate. In some cases, the hydrogenconsumption rate is adjusted at least in part based on the temperatureof the ammonia reformer. In some cases, the hydrogen consumption rate isreduced when the temperature of the one or more combustion heaters ofthe ammonia reformer or the ammonia reformer starts to decrease, so thatmore hydrogen is provided to the one or more combustion heaters. In somecases, the hydrogen consumption rate is increased when the temperatureof the one or more combustion heaters of the ammonia reformer or theammonia reformer starts to increase, so that less hydrogen is providedto the one or more combustion heaters.

In some cases, the hydrogen consumption rate of the fuel cell ismaintained within the selected tolerance of a target hydrogenconsumption rate and one or more air flow rates comprising at leastoxygen provided by one or more air supply units is adjusted to maintainthe auto-thermal reforming process of the ammonia reformer. In somecases, the one or more air flow rates are reduced when the temperatureof the one or more combustion heaters of the ammonia reformer, or thetemperature of the ammonia reformer, starts to increase (so that lessoxygen is provided to the one or more combustion heaters). In somecases, the one or more air flow rates are increased when the temperatureof the one or more combustion heaters of the ammonia reformer or theammonia reformer starts to decrease (so that more oxygen is provided tothe one or more combustion heaters). In some cases, both the hydrogenconsumption rate of the fuel cell and the one or more air flow rates areadjusted simultaneously based at least in part on the temperature of theone or more combustion heaters of the ammonia reformer and/or thetemperature of the ammonia reformer.

The one or more features may increase the output voltage of the fuelcell. The increase in the output voltage of the fuel cell may be incomparison to an equivalent fuel cell without the one or more features.In some cases, the one or more features increase the output voltage byat least 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. Insome cases, the one or more features increase the output voltage by atmost 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%.

The one or more features may increase a power density of the fuel cell.The increase in the power density of the fuel cell may be in comparisonto an equivalent fuel cell without the one or more features. In somecases, the one or more features may increase the power density by atleast 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. In somecases, the one or more features may increase the power density by atmost 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. The powerdensity of the fuel cell can be at least about 0.1, 0.5, 1, 2, 3, 4, 5,6, 7, 8, 9, 10, 20, or 30 kW/L (i.e., a ratio of an electrical poweroutput to a volume of one or more fuel cells or one or more fuel cellstacks). The power density of the fuel cell can be at most about 0.1,0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

The one or more features may reduce a physical footprint (e.g.,size/volume, weight, etc.) of a fuel cell. The reduced footprint mayenable the fuel cell to be integrated into applications where a lighterweight and/or smaller volume is desirable (e.g., aerial vehicles), orinto applications where the size is limited and power requirements arehigh (e.g., some industrial vehicles). In some embodiments, the fuelcell comprising the one or more features can be configured to provide aratio of an electrical power output of the fuel cell to a projectedsurface area of the anode that is at least about 0.05 W/cm². In someembodiments, the ratio can be at least about 0.1, 0.15, 0.2, 0.25, 0.3,0.35, or 0.4 W/cm². In some embodiments, the ratio can be at most about0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4 W/cm². The ratio may be based onthe anode channel receiving a first continuous stream comprising about25% nitrogen and about 75% hydrogen by moles, and the cathode channelreceiving a second continuous stream comprising at least 20% oxygen bymoles (e.g., air). In some cases, the ratio can be based on the firstcontinuous stream comprising a hydrogen flow rate of at least about0.001, 0.01, 0.1, 1, 10, 100, 1000, 10000, or 100000 mole per second. Insome cases, the ratio can be based on the second continuous streamcomprising an oxygen flow rate of at least about 0.0001, 0.001, 0.01,0.1, 1, 10, 100, 1000, 10000, 100000, 1000000 mole per second. In somecases, the ratio can be based on the first continuous stream comprisinghydrogen and nitrogen from the ammonia reformer. The projected surfacearea may be construed as the largest possible surface area of the anodeprojected onto a flat plane. The projected surface area can be a surfacearea of the largest surface of the anode. The largest surface can bedefined at the largest flat surface of the anode.

FIG. 6 schematically illustrates a stack or module of fuel cells (601)comprising a plurality of fuel cells, in accordance with someembodiments. Each fuel cell of the plurality of fuel cells may compriseone or more components. The one or more components may comprise one ormore channels for a cathode (e.g., for flowing air), a currentcollecting layer for the cathode, and a gas diffusion layer (603; GDL)for the cathode. In some embodiments, the one or more components mayfurther comprise a gas diffusion layer (605; GDL) for an anode and acurrent collecting layer for the anode (606). In some cases, the one ormore components may further comprise an electrolyte (604) disposedbetween the GDL (603) of the cathode and the GDL (605) of the anode. Theplurality of fuel cells can be adjacently coupled with one another.

The fuel cell design may be adapted for use in one or more fuel cellstacks or modules comprising one or more fuel cells. The fuel cellmodule may comprise a stack of fuel cells or multiple stacks of fuelcells. The fuel cells may be arranged in a lateral configuration or acircular configuration. The fuel cells in the fuel cell stack may bearranged on top of each other and/or next to each other. Each of thefuel cells may comprise one or more inlets for receiving a sourcematerial. The fuel cell stack or the one or more fuel cells of the fuelcell stack may be in fluid communication with the ammonia reformer orreactor in order to receive the source materials to generateelectricity. The fuel cells may be coupled in sequence or in parallel.In some cases, the one or more fuel cell stacks or modules may be inseries or in parallel fluid communication with each other. The fuelcells may be configured to process the source material to generateelectrical energy. The fuel cells stack or module (e.g., 601) cancomprise any number of fuel cells. For instance, the fuel cells cancomprise at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 200, 300, 400, 500,600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000,9000, 10,000 fuel cells. The fuel cells can comprise at most 2, 3, 4, 5,6, 7, 8, 9, 10, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000,3000, 4000, 5000, 6000, 7000, 8000, 9000, 10,000 fuel cells.

FIG. 7 schematically illustrates durability testing results for a stackof fuel cells with a multi-layer gas diffusion layer design providedwith a mixture of hydrogen and nitrogen, in accordance with someembodiments. The durability testing was conducted using a fuel cellstack comprising 32 fuel cells and a gas diffusion layer comprising adouble layer design. A gaseous mixture of hydrogen and nitrogen(comprising a hydrogen to nitrogen volume ratio of 3:1) was provided tothe fuel cell stack for a one-hour endurance test. The gaseous hydrogenwas provided at a volumetric flow rate of 15 standard liters per minuteand the gaseous nitrogen was provided at a volumetric flow rate of 5standard liters per minute. As shown in the plot in FIG. 7 , the poweroutput of the fuel cell stack stabilized at about 572 Watts.

FIG. 8 schematically illustrates durability testing results for a stackof fuel cells with a multi-layer gas diffusion layer design providedwith a mixture of hydrogen and nitrogen produced from an ammoniareforming process (3:1 hydrogen to nitrogen volume ratio), in accordancewith some embodiments. An ammonia concentration in the hydrogen mixturemay be maintained at less than 1 ppm. A stack of five fuel cells wastested using the gas mixture produced during an ammonia reformingprocess. No appreciable differences in fuel cell performance wereobserved between a first test scenario involving the processing ofreformate gases produced during ammonia reforming, and a second testscenario involving the processing of a mixture of hydrogen and nitrogenfrom a gas tank. Further, no major degradations in fuel cell performancewere observed over the operational time period.

The fuel cells in a stack can be electrically coupled. The fuel cellscan be electrically coupled in series to provide higher voltage. In somecases, a fuel cell can provide at least about 0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1.0, 1.1, or 1.2 V in output voltage. In some cases,a fuel cell can provide at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,0.8, 0.9, 1.0, 1.1, or 1.2 in output voltage. Fuel cells electricallycoupled in series can provide a total output voltage that is equal toabout the sum of the output voltage of each of the fuel cells coupled inseries. For instance, a plurality of fuel cells can provide at leastabout 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90,100, 200, 300, 400, 500, 600, 700, 800, or 900 V. A plurality of fuelcells can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900kV. A plurality of fuel cells can provide at least about 1, 2, 3, 4, 5,6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500,600, 700, 800, or 900 MV. A plurality of fuel cells can provide at mostabout 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90,100, 200, 300, 400, 500, 600, 700, 800, or 900 V. A plurality of fuelcells can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900kV. A plurality of fuel cells can provide at most about 1, 2, 3, 4, 5,6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500,600, 700, 800, or 900 MV.

The fuel cells can be electrically coupled in parallel to provide ahigher current. A fuel cell can provide at least about 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 A. A fuel cell canprovide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60,70, 80, 90, or 100 A. Fuel cells electrically coupled in parallel canprovide a total output current that is equal to the sum of the outputcurrent of each of the fuel cells coupled in parallel. For instance, aplurality of fuel cells can provide at least about 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600,700, 800, or 900 A. A plurality of fuel cells can provide at least about1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200,300, 400, 500, 600, 700, 800, or 900 kA. A plurality of fuel cells canprovide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50,60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 MA. Aplurality of fuel cells can provide at most about 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600,700, 800, or 900 A. A plurality of fuel cells can provide at most about1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200,300, 400, 500, 600, 700, 800, or 900 kA. A plurality of fuel cells canprovide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60,70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 MA.

One or more ammonia reformers can be configured to provide a pluralityof streams comprising hydrogen and nitrogen to the plurality of the fuelcells. In some embodiments, the one or more ammonia reformers compriseone ammonia reformer. In some embodiments, the one or more ammoniareformers comprise at least 2, 3, 4, 5, 6, 7, 8, 9, or 10 ammoniareformers.

In some embodiments, at least one fuel cell of the plurality of fuelcells outputs a different electrical power than other fuel cells of theplurality of fuel cells. In some cases, at least one fuel cell of theplurality of fuel cells is configured to reduce an electrical poweroutput while others of the plurality of fuel cells maintain theirrespective power outputs. For example, one or more fuel cells of theplurality of fuel cells can operationally or intermittently reduce poweroutput to about 0% to 50% of a first power level, while the other fuelcells of the plurality of fuel cells output about 50% to 100% of thefirst power level. In some cases, at least one fuel cell of theplurality of fuel cells is configured increase an electrical poweroutput while others of the plurality of fuel cells maintain theirelectrical power outputs.

In some cases, a system comprising the plurality of fuel cells can beconfigured to detect a fault in at least one fuel cell of the pluralityof fuel cell. The fault can be detected via, for example, a temperaturesensor, a voltage sensor, a current sensor, a pressure sensor, a flowsensor, etc., that is operatively coupled to the at least one fuel celland a controller. In some cases, after detecting a fault, at least onefuel cell of the plurality of fuel cells is configured to shut down orreduce power generation based on the fault, and/or an inlet flow of theat least one fuel cell is configured to be reduced or shut down based onthe fault, while the other fuel cells of the plurality of fuel cells cancontinue to output electrical power. The controller can operate the atleast one fuel cell to reduce or shut down the inlet flow. In somecases, the fault may comprise a temperature of the inlet flow beinggreater than a threshold temperature, an ammonia concentration beinggreater than a threshold concentration, a pressure of the inlet flowbeing greater than a threshold pressure, a decrease in voltage below athreshold voltage, an inlet flow rate less than or greater thanthreshold flow rates, etc. In some cases, after the fault is at leastpartly resolved, the controller can operate the at least one fuel cellto increase the inlet flow or power generation. In some cases, the faultis at least partly resolved when at least one of: a temperature of theinlet flow returns to a target temperature range, an ammoniaconcentration returns to below a threshold concentration, a pressure ofthe inlet flow returns to a target pressure range, voltage level returnsto a target voltage range, or an inlet flow returns to a target flowrate range.

In some embodiments, the plurality of fuel cells comprises at least onefuel cell that is different in size, power output, hydrogen consumptionrate, power density, or operating temperature from others of theplurality of fuel cells. In some embodiments, the plurality of fuel cellstacks or modules comprises at least one fuel cell stack or module thatis different in size, power output, hydrogen consumption rate, powerdensity, or operating temperature from others of the plurality of fuelcell stacks or modules.

In some embodiments, at least one fuel cell of the plurality of the fuelcells is in serial fluid communication with at least one other fuel cellof the plurality of the fuel cells. For example, exit flows of one ormore fuel cells of the plurality of fuel cells can provide the inletflows of one or more other fuel cells of the plurality of fuel cells. Insome cases, at least one fuel cell of the plurality of the fuel cells isdifferent in size, power output, hydrogen consumption rate, powerdensity, or operating temperature from at least one other fuel cell ofthe plurality of the fuel cells that are in serial fluid communication.

In some embodiments, at least one fuel cell of the plurality of the fuelcells is in parallel fluid communication to at least one other fuel cellof the plurality of the fuel cells. In some cases, at least one fuelcell of the plurality of the fuel cells is different in size, poweroutput, hydrogen consumption rate, power density, or operatingtemperature from at least one other fuel cell of the plurality of thefuel cells that are in parallel fluid communication.

In some embodiments, at least one fuel cell stack or module of theplurality of fuel cell stacks or modules is in serial fluidcommunication to at least one other fuel cell stack or module of theplurality of fuel cell stacks or modules. For example, exit flows of oneor more fuel cell stacks or modules of the plurality of fuel cell stacksor modules can provide the inlet flows of one or more other fuel cellstacks or modules of the plurality of fuel cell stacks or modules. Insome cases, at least one fuel cell stack or module of the plurality ofthe fuel cell stacks or modules is different in size, power output,hydrogen consumption rate, power density, or operating temperature fromat least one other fuel cell stack or module of the plurality of thefuel cell stacks or modules that are in serial fluid communication. Forexample, a first fuel cell stack that outputs an exit flow to an inletflow of a second fuel cell stack may be in larger in size or may outputa higher power.

In some embodiments, at least one fuel cell stack or module of theplurality of fuel cell stacks or modules is in parallel fluidcommunication to at least one other fuel cell stack or module of theplurality of the fuel cell stacks or modules. In some cases, a flowcomprising the source material may be distributed between two or morefuel cell stacks or modules of the plurality of fuel cell stacks ormodules within at least about 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%,80%, 90%, or 100% of a target flow rate (e.g., target inlet flow rate ofa single fuel cell stack). In some cases, a flow comprising the sourcematerial may be distributed between two or more fuel cell stacks ormodules of the plurality of fuel cell stacks or modules within at mostabout 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of atarget flow rate. In some cases, a flow comprising the source materialmay be distributed between two or more fuel cell stacks or modules ofthe plurality of fuel cell stacks or modules by a distribution factor.For example, when the distribution factor is about 4 to 5, a first fuelcell stack may receive a flow comprising the source material that isabout 4 to 5 times higher (e.g., by weight, volume, moles, orconcentration of the source material) than a second fuel cell stack. Insome cases, the distribution factor may be at least about 0.1, 0.5, 1,2, 3, 4, 5, 6, 7, 8, 9, or 10. In some cases, the distribution factormay be at most about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In somecases, at least one fuel cell stack or module is different in size,power output, hydrogen consumption rate, power density, or operatingtemperature from at least one other fuel cell stack or module of theplurality of the fuel cell stacks or modules that are in parallel fluidcommunication.

In some cases, the fuel cell may be operated to intermittently reducethe hydrogen consumption rate (thus increasing the flow rate ofunconverted hydrogen exiting the fuel cell) to purge out at least one ofhydrogen, nitrogen, or water. The hydrogen consumption rate can bereduced by directing at least a part of a first continuous stream ofhydrogen and nitrogen to the ammonia reformer. In some cases, the firstcontinuous stream can be in direct fluidic communication with the one ormore combustion heaters of the ammonia reformer. In some cases, at leastthe part of the first continuous stream can be flared at one or morecombustion exhausts of one or more combustion heaters. In some cases, atleast the part of the first continuous stream comprising hydrogen isvented out of one or more combustion exhausts of the one or morecombustion heaters.

The one or more combustion heaters can be in operable communication withthe ammonia reformer for heating the ammonia reformer. The one or morecombustion heaters can be in fluidic communication with the fuel cell toreceive the at least the part of the first continuous stream.

The one or more features can be configured to facilitate purging of aselect material from the anode gas diffusion layer. The select materialcan comprise one or more of nitrogen, ammonia, water, or one or moreimpurities. In some cases, the fuel cell can comprise one or more exitports for discharging the select material and unconverted hydrogen fromthe fuel cell. In some cases, unconverted hydrogen from the plurality offuel cells can be directed to the at least one ammonia reformer orreactor for combustion heating. One or more air supply units can provideat least oxygen to the ammonia reformer for combustion of theunconverted hydrogen. In some cases, unconverted oxygen from theplurality of fuel cells (e.g., one or more cathode exit flows) canprovide at least oxygen to the ammonia reformer for combustion of theunconverted hydrogen. In some cases, water may be removed from thestream comprising the unconverted hydrogen prior to combusting theunconverted hydrogen. In some cases, the stream comprising theunconverted hydrogen can be flared. The systems and the methodsdisclosed herein may be implemented using one or more fuel cells. Theone or more fuel cells may be arranged in a fuel cell stack as disclosedelsewhere herein. In some non-limiting embodiments, the one or more fuelcells may comprise an anode, a cathode, and an electrolyte disposedbetween the anode and the cathode. In some cases, the anode may comprisea gas diffusion layer with one or more channels for directing a sourcematerial through the gas diffusion layer of the anode to facilitateprocessing of the source material to generate an electrical current. Insome cases, the one or more channels may comprise one or more surfacefeatures configured to enhance a diffusion of the source materialthrough the gas diffusion layer of the anode. The source material maycomprise, for example, a gaseous mixture of hydrogen and nitrogen. Insome cases, processing the source material may comprise dissociating oneor more hydrogen molecules of the source material into one or moreprotons and one or more electrons.

In some embodiments, the one or more fuel cells may be in fluidcommunication with one or more reactor modules for catalyticallydecomposing ammonia. The one or more fuel cells may be configured toreceive hydrogen and/or nitrogen produced or extracted using the one ormore reactor modules, and to process the hydrogen/nitrogen mixture togenerate electrical energy.

In some cases, the fuel cells may be in fluid communication with one ormore reactors. The one or more reactors may be configured tocatalytically decompose ammonia to generate hydrogen. The exit flow fromthe one or more reactors may comprise hydrogen, nitrogen, and/orunconverted ammonia. The exit flow from the one or more reactors may bedirected to the one or more fuel cells, which may be configured to use(i.e., process) the exit flow or any portion thereof to generateelectrical energy.

In an aspect, the present disclosure provides a method for processinghydrogen. The method may comprise providing a reactor exit flowcomprising hydrogen and/or nitrogen to one or more fuel cells. Thereactor exit flow may be from a reactor or a reformer for catalyticallydecomposing ammonia. In some cases, the reactor exit flow may be fromvarious components or subcomponents of a reformer for catalyticallydecomposing ammonia. The various components or subcomponents maycomprise, for example, a reactor, an adsorbent tower, or a heatexchanger of the reformer. The method may further comprise using the oneor more fuel cells to process the reactor exit flow to generateelectricity (i.e., an electrical current).

In some cases, the exit flow from the one or more reactors may bedirected to one or more adsorbents to remove excess or trace ammoniabefore the reactor exit flow is directed to the one or more fuel cells.The adsorbents may help to preserve a performance and/or a longevity ofthe one or more fuel cells since ammonia can be detrimental to the fuelcells. The adsorbents may be replaceable (e.g., as cartridges) after acertain number of cycles or operations. In some embodiments, aconcentration of ammonia in the exit flow from the one or moreadsorbents may be further reduced (before supplying the exit flow fromthe one or more adsorbents to the one or more fuel cells) using anadditional ammonia filtration system in series fluidic communicationwith the one or more adsorbents. The additional ammonia filtrationsystem may be an adsorbent-based, membrane-based, absorbent-based, asolvent-based, a water-based, or an acidic-based ammonia filtrationsystem. In some cases, the additional ammonia filtration systemcomprises one or more ammonia filtration cartridges, so that when one ormore cartridges are fully or at least partially spent, the one or morefully or at least partially spent cartridges can be replaced with one ormore new ammonia filtration cartridges.

In some cases, the fuel cells may be in fluid communication with aplurality of adsorption towers. The plurality of adsorption towers maycomprise at least a first adsorption tower and a second adsorptiontower. The first and/or second adsorption tower may be used to removeany traces of ammonia from the reactor exit flow before the reactor exitflow is directed to the one or more fuel cells. While the firstadsorption tower is being used, the second adsorption tower may beregenerated (e.g., such that ammonia is desorbed from the secondadsorption tower). Once the first adsorption tower is fully saturated(e.g., when the first adsorption tower is not able to adsorb additionalammonia), the second adsorption tower may be partially or fullyregenerated and ready for use in another cycle or operation. In any ofthe embodiments described herein, two, three, four, five, six, seven,eight, nine, ten, or more adsorption towers may be used to filter thereactor exit flow before the reactor exit flow reaches the one or morefuel cells.

Proton-Exchange Membrane Fuel Cells

The fuel cells disclosed herein may comprise various types of fuelcells. In some cases, the electrolyte can comprise a membrane. In somecases, the membrane can comprise a proton-exchange membrane. In somecases, the fuel cells may comprise one or more proton-exchange membranefuel cells (PEMFCs) having a proton-conducting polymer electrolytemembrane. A proton exchange membrane fuel cell can be used to transformchemical energy into electrical energy by electrochemically reactinghydrogen and oxygen. In some cases, the PEMFC may comprise aproton-conducting polymer membrane that separates the anode and cathodesides of the PEMFC. In some cases, the fuel cells may comprise one ormore PEMFCs, one or more solid oxide fuel cells (SOFCs), one or moremolten carbonate fuel cells (MCFCs), one or more alkaline fuel cells(AFCs), one or more alkaline membrane fuel cells (AMFCs), or one or morephosphoric acid fuel cells (PAFCs).

The fuel cells of the present disclosure may comprise one or more PEMFCsthat are adapted for use with a mixture of hydrogen and/or nitrogen. Insome cases, the fuel cells of the present disclosure may be used togenerate electrical energy from hydrogen gas mixtures containingimpurities that would otherwise degrade the performance of conventionalfuel cells (some of which may require up to about 99.7% pure hydrogen asa source material). The fuel cells of the present disclosure may providebetter performance compared to fuel cells with a dead-end type design(e.g., a fuel cell without an outlet at the anode channel configured todirect unconverted hydrogen and/or nitrogen out of the fuel cell). Thedead-end type design does not allow efficient processing of H₂/N₂mixtures since N₂ concentrations may build up without appropriatepurging. The fuel cells of the present disclosure may provide betterperformance compared to fuel cells with an intermittent purgingoperation that does not allow efficient processing of H₂/N₂ mixtures(since N₂ concentrations may build up without continuous purging). Insome cases, the continuous purging may be defined based on purging timeratio (a ratio of total purging time to total operational time whileelectricity is being generated by the one or more fuel cells). In somecases, one or more fuel cells are continuously purged when the purgingtime ratio is at least about 0.5 (i.e., purging of N₂ occurs during atleast about 50% of the total operational time). In some cases, one ormore fuel cells are continuously purged when the purging time ratio isat least about 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases,the purging time ratio is about 1 (i.e., the purging of N₂ occurs duringabout 100% of the total operational time). The fuel cells disclosedherein may also provide enhanced performance compared to fuel cells witha flow-through design (e.g., a fuel cell with an outlet at the anodechannel configured to direct unconverted hydrogen and/or nitrogen out ofthe fuel cell) that allows H₂/N₂ mixtures, since the fuel cells in suchflow-through designs can experience fuel starvation if excess H₂/N₂mixture is not provided or H₂ from H₂/N₂ mixture is not distributed wellin the anode. The presently disclosed fuel cells may be configured toutilize and process a H₂/N₂ mixture without experiencing similardegradations in performance that can be attributed to a buildup of N₂concentrations. Such advantages may be realized using, for example,optimally configured anode channels for the fuel cells (e.g., such asanode channels including cuts, cutouts, or grooves).

Source Material

In an aspect, the present disclosure provides a fuel cell design thatcan be compatible with various gas mixtures containing hydrogen,nitrogen, ammonia, and/or other reformate gases. Such gas mixtures maybe provided by an ammonia reformer or a reactor configured to process(i.e., catalytically decompose) ammonia. Although hydrogen has arelatively high gravimetric density (measured in MJ/kg), fuel storagesystems for compressed and liquefied hydrogen are often complex due tothe need to provide and maintain specialized storage conditions. Forexample, storage of hydrogen as a gas may require high-pressure tanks(e.g., 350-700 bar or 5,000-10,000 psi). Storage of hydrogen as a liquidmay require cryogenic temperatures because the boiling point of hydrogenat a pressure of 1 atm is −252.8° C. Using ammonia as a hydrogen carriermay provide several benefits over storing and transporting purehydrogen, including easy storage at relatively standard conditions (0.8MPa, 20° C. in liquid form), and convenient transportation. Ammonia alsohas a relatively high hydrogen content (17.7 wt % or 120 grams of H₂ perliter of liquid ammonia). Further, the production of ammonia using theHaber-Bosch process can be powered by renewable energy sources (e.g.,solar photovoltaic, solar-thermal, wind turbines, geothermal, and/orhydroelectricity), which makes the production process environmentallysafe and friendly, as N₂ is the only byproduct and there is no furtheremission of CO₂. Once the ammonia is produced, the ammonia may beprocessed to release the hydrogen through a dehydrogenation process(i.e., by dissociating, decomposing, reforming, or cracking theammonia).

The source material can comprise various concentrations of hydrogen,nitrogen, and ammonia. When the source material is provided directlyfrom an ammonia reformer, the ratio of nitrogen to hydrogen can be about1 part nitrogen to 3 parts hydrogen by moles. There can be some ammoniain the source material, depending on the extent of conversion of theammonia by the reformer. In some cases, the source material can be mixedwith another gas before being provided to the one or more fuel cells.For instance, the source material can be mixed with a stream of highpurity hydrogen gas (e.g., greater than 99% purity). The source materialcan be mixed with a stream of high purity nitrogen gas (e.g., greaterthan 99% purity). The source material can be purified before beingprovided to the one or more fuel cells. For instance, the sourcematerial can be contacted with an adsorbent or an absorbent to reduceammonia concentration in the source material. In some cases, the sourcematerial can be provided by mixing high purity nitrogen and high purityhydrogen streams. Therefore, the concentrations and the amounts ofhydrogen, nitrogen, and ammonia that is supplied to the one or more fuelcells can be varied.

FIG. 15 schematically illustrates ammonia as an energy carrier andvarious density characteristics of ammonia in comparison to other typesof fuel. The H₂ storage capacity of NH₃ is about 17.7 wt % and 120 gramsof H₂ per liter of ammonia. Compared to other fuel types such ashydrogen, ammonia exhibits a favorable volumetric density in view of itsgravimetric density. Further, in comparison to other types of fuel(including carbon-based fuels such as methane, propane, methanol,ethanol, gasoline, E-10 gasoline, JP-8 jet fuel, or diesel), the use ofammonia as a fuel may not produce harmful emissions such as CO₂, CO, orblack carbon (soot), and may produce zero or negligible NOx (e.g., NO₂or N₂O) emissions (especially in combination with a selective catalyticreduction [SCR] catalyst). Thus, the use of ammonia as an energy carrierallows some embodiments of the presently disclosed systems and methodsto leverage the benefits of hydrogen fuel (e.g., environmentally safeand high gravimetric energy density) once the ammonia is decomposed intohydrogen, while taking advantage of (a) ammonia's greater volumetricdensity compared to hydrogen and (b) the ability to transport ammonia atstandard temperatures and pressures without requiring the complex andhighly pressurized storage vessels typically used for storing andtransporting hydrogen.

In some embodiments, the source material comprises a volume fraction ofH₂ of about 30% to about 99.7%. In some embodiments, the source materialcomprises a volume fraction of H₂ of from about 30% to about 99.99%. Insome embodiments, the source material comprises a volume fraction of H₂of from about 70% to about 990.999%. In some embodiments, the sourcematerial comprises a volume fraction H₂ of from about 70% to about 80%when provided by ammonia reforming. In some embodiments, one or morehydrogen separation systems (e.g., pressure swing adsorption (PSA) ormembrane separation) can be used to increase the volume fraction ofhydrogen in the source material.

In some embodiments, the source material comprises a volume fraction ofH₂ of about 30%, about 35%, about 40%, about 45%, about 50%, about 55%,about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about90%, about 95%, about 99.7%, or any value therebetween. In someembodiments, the source material comprises a volume fraction of H₂ of atleast about 1%, about 5%, about 10%, about 15%, about 20%, about 25%,about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%,about 95%, about 99.7%, or any value therebetween. In some embodiments,the source material comprises a volume fraction of H₂ of at most about1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%,about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%,about 99.7%, or any value therebetween. In some embodiments, the sourcematerial comprises a volume fraction of H₂ of about 30% to about 99.7%,about 35% to about 95%, about 40% to about 90%, about 45% to about 85%,about 50% to about 80%, about 55% to about 75%, about 60% to about 70%,about 65% to about 95%.

In some embodiments, the source material comprises a molar fraction ofH₂ of at least about 1%, about 5%, about 10%, about 15%, about 20%,about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%,about 90%, about 95%, about 99.7%, or any value therebetween. In someembodiments, the source material comprises a molar fraction of H₂ of atmost about 1%, about 5%, about 10%, about 15%, about 20%, about 25%,about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%,about 95%, about 99.7%, or any value therebetween.

In some embodiments, the source material comprises a partial pressurefraction of H₂ of at least about 1%, about 5%, about 10%, about 15%,about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%,about 85%, about 90%, about 95%, about 99.7%, or any value therebetween.In some embodiments, the source material comprises a partial pressurefraction of H₂ of at most about 1%, about 5%, about 10%, about 15%,about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%,about 85%, about 90%, about 95%, about 99.7%, or any value therebetween.

The source material can comprise various concentrations of nitrogen. Insome cases, the source material comprises comprise a volume fraction ofnitrogen of at least 10%. In some cases, the source material comprises avolume fraction of nitrogen of at least 20%. In some cases, the sourcematerial comprises a volume fraction of nitrogen ranging from about 20%to about 30%. In some cases, the source material comprises a volumefraction of nitrogen ranging from about 30% to about 50%. In some cases,the source material comprises a volume fraction of nitrogen ranging fromabout 40% to about 70%. In some embodiments, the source materialcomprises a volume fraction of nitrogen of about 10%, about 15%, about20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%,about 55%, about 60%, about 65%, about 70%, or any value therebetween.In some embodiments, the source material comprises a volume fraction ofnitrogen of at least about 10%, about 15%, about 20%, about 25%, about30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%,about 65%, about 70%, or any value therebetween. In some embodiments,the source material comprises a volume fraction of nitrogen of at mostabout 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%,or any value therebetween. In some embodiments, the source materialcomprises a volume fraction of nitrogen of about 10% to about 70%, about15% to about 65%, about 20% to about 60%, about 25% to about 55%, about30% to about 50%, about 35% to about 45%, about 40% to about 70%, or anyvalue therebetween.

In some embodiments, the source material comprises a partial pressurefraction of N₂ of at least about 1%, about 5%, about 10%, about 15%,about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%,about 85%, about 90%, about 95%, about 99%, or any value therebetween.In some embodiments, the source material comprises a partial pressurefraction of N₂ of at most about 1%, about 5%, about 10%, about 15%,about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%,about 85%, about 90%, about 95%, about 99%, or any value therebetween.

In some embodiments, the source material comprises a molar fraction ofN₂ of at least about 1%, about 5%, about 10%, about 15%, about 20%,about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%,about 90%, about 95%, about 99%, or any value therebetween. In someembodiments, the source material comprises a molar fraction of N₂ of atmost about 1%, about 5%, about 10%, about 15%, about 20%, about 25%,about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%,about 95%, about 99%, or any value therebetween.

The source material can comprise various concentrations of ammonia. Insome embodiments, the source material comprises an ammonia concentrationthat is less than about 0.1 ppm, about 0.2 ppm, about 0.3 ppm, about 0.4ppm, about 0.5 ppm, about 0.6 ppm, about 0.7 ppm, about 0.8 ppm, about0.9 ppm, about 1 ppm, about 1.2 ppm, about 1.4 ppm, about 1.6 ppm, about1.8 ppm, about 2 ppm, or any value therebetween. In some embodiments,the source material comprises an ammonia concentration that is at mostabout 0.1 ppm, about 0.2 ppm, about 0.3 ppm, about 0.4 ppm, about 0.5ppm, about 0.6 ppm, about 0.7 ppm, about 0.8 ppm, about 0.9 ppm, about 1ppm, about 1.2 ppm, about 1.4 ppm, about 1.6 ppm, about 1.8 ppm, about 2ppm, or any value therebetween. In some embodiments, the source materialcomprises an ammonia concentration that is between about 0.1 ppm andabout 2 ppm, between about 0.2 ppm and about 1.8 ppm, between about 0.3ppm and about 1.6 ppm, between about 0.4 ppm and about 1.4 ppm, betweenabout 0.5 ppm and about 1.2 ppm, between about 0.6 ppm and about 1 ppm,between about 0.7 ppm and about 0.9 ppm, or between about 0.8 ppm andabout 2 ppm. In some embodiments, an ammonia concentration in the firstcontinuous stream is at most 1000, 900, 800, 700, 600, 500, 400, 300,200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or1 ppm. In some embodiments, an ammonia concentration in the firstcontinuous stream is at least 1000, 900, 800, 700, 600, 500, 400, 300,200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or1 ppm.

The source material can be provided to one or more fuel cells at variouspressures. The source material can be provided to one or more fuel cellsat an absolute pressure of at least about 0.5, 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 15, 20, 25, 30, or 40 bar. The source material can be provided toone or more fuel cells at an absolute pressure of at most about 0.5, 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or 40 bar. The sourcematerial can be provided to one or more fuel cells at an absolutepressure of about 1 to 5 bar. The pressure of the source material can bemaintained within a selected tolerance while the source material isbeing provided to the one or more fuel cells. The selected tolerance canbe 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 150, 200, 300,400, 500, or 1000 percent of the absolute pressure. The pressure or theflow rate of the source material can be modulated while the sourcematerial is being provided to the one or more fuel cells. One or moreflow regulators, pressure regulators, control units, or any combinationthereof can be used to modulate the pressure or the flow rate. Forexample, one or more pressure regulators can reduce the pressure of thesource material provided to the one or more fuel cells from an absolutepressure of about 5 to 10 bar to about 1.5 to 3 bar. The one or moreflow regulators, pressure regulators, control units, or any combinationthereof can be positioned upstream or downstream of the fuel cell. Theone or more flow regulators, pressure regulators, control units, or anycombination thereof can be positioned downstream of the fuel cell toprevent or reduce a back flow of the unconverted hydrogen or any otherflows.

In some cases, the source material can be provided to a plurality offuel cells, fuel cell stacks, or fuel cell modules as a plurality ofstreams. The flow rates or the pressures of the plurality of streams canbe maintained or modulated. One or more flow regulators, pressureregulators, control units, or any combination thereof can be used tomodulate the pressures or the flow rates. In some cases, at least onefuel cell of the plurality of the fuel cells can receive a stream at aflow rate that is different from the flow rates of other streams of theplurality of streams. In some cases, each of the plurality of the fuelcells can receive one of the plurality of streams at a flow rate that isabout the same as or within a selected tolerance of other flow rates ofothers of the plurality of streams. In some cases, the selectedtolerance is about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%. In somecases, the selected tolerance is at most about 10, 20, 30, 40, 50, 60,70, 80, 90, or 100%.

Reformer

FIG. 9 schematically illustrates a block diagram of an exemplary systemfor processing a source material 910 to produce electrical energy. Thesource material 910 may comprise hydrogen. In some cases, the sourcematerial 910 may further comprise one or more other gases, such as, forexample, oxygen (O₂), nitrogen (N₂) and/or ammonia (NH₃). The sourcematerial 910 may comprise one or more reformate gases that are generatedby an ammonia processing system. The system can be configured to crackor decompose a hydrogen carrier (e.g., ammonia, a liquid organichydrogen carrier (LOHC), formic acid (HCOOH), or methanol (CH₃OH)) toextract or produce hydrogen. In some cases, the source material 910 maycomprise various impurities, such as unconverted ammonia that has passedthrough the ammonia processing system, nitrogen that has mixed with thehydrogen extracted using the ammonia processing system, and/or othertrace materials within the ammonia processing system.

The source material 910 may be provided to a fuel cell 920. The fuelcell 920 may be designed or configured to process the hydrogen toproduce electrical energy 930. The electrical energy 930 may be used topower various system, vehicles, and/or devices, including, for example,terrestrial, aerial, aquatic, marine, submarine, or amphibious vehicles,mobile or stationary electric devices, or a stationary electrical grid.In some cases, the electrical energy 930 may be used as back-up powerfor the various systems, vehicles, and/or devices.

As described above, the one or more fuel cells 920 may be used togenerate electrical energy 930 (e.g., an electrical current or a flow ofelectrons) using the source material 910, which may comprise hydrogenand/or nitrogen. In some cases, the one or more fuel cells may generatethe electrical energy 930 through an electrochemical reaction of a fuel.The fuel may comprise the hydrogen in the source material 910. Theelectricity generated by the fuel cells may be used to power one or moresystems, vehicles, or devices. In some embodiments, excess electricitygenerated by the fuel cells may be stored in one or more energy storageunits (e.g., batteries) for future use. In some embodiments, the fuelcells may be provided as part of a larger fuel cell system.

In some non-limiting examples, the fuel cell system may comprise anelectrolysis module. Electrolysis of a byproduct of the one or more fuelcells (e.g., water) may allow the byproduct to be removed throughdecomposition of the byproduct into one or more constituent elements(e.g., oxygen and/or hydrogen). Electrolysis of the byproduct can alsogenerate additional fuel (e.g., hydrogen) for the fuel cell. The energyrequired to run the electrolysis module can, in part, come from excesselectricity sources including, but not limited to, solar power, windpower, hydro power, nuclear power, combustion engines, combustionturbines, steam turbines, etc. In some cases, the fuel cell may receivethe source material from one or more reformers. The one or morereformers may be configured to perform a catalytic decomposition orcracking of ammonia to extract and/or produce hydrogen. The exit flowfrom the reformers may comprise the extracted hydrogen and/or othergases (e.g., nitrogen and/or ammonia). The exit flow may correspond tothe source material usable by the fuel cells to generate electricalenergy. In some cases, the reformers may be operated using heat energy.In some cases, the reformers may be heated using a combustor thatgenerates heat energy to drive the operation of the reformers. In somecases, the heat energy may be generated from the combustion of achemical compound (e.g., hydrogen or a hydrocarbon). The hydrogen thatis generated and/or extracted using the reformers may be provided to theone or more fuel cells, which may produce electrical energy to power oneor more systems, sub-systems, or devices requiring electrical energy tooperate. In some cases, the hydrogen generated and/or extracted usingthe reformers may be provided to one or more other reactors orreformers. In such cases, the one or more other reactors or reformersmay be configured to combust the hydrogen to generate thermal energy.Such thermal energy may be used to heat the one or more other reactorsor reformers to facilitate a further catalytic decomposition or crackingof ammonia to extract and/or produce additional hydrogen. In some cases,the reformers or reactors may be heated using electrical heating,resistive heating, or Joule heating. In some cases, the reformers orreactors may be heated using the combustion heating and electricalheating, resistive heating, or Joule heating. In such cases, a currentmay be passed through an electrical heater, a catalyst, or a catalystbed of the reformer to heat the catalyst directly.

FIG. 10 schematically illustrates a process for feeding reformate gas toa fuel cell, in accordance with some embodiments. The reformate gas maycomprise a mixture of hydrogen and nitrogen. The mixture may comprise aratio of hydrogen gas to nitrogen gas by weight or volume. The ratio maybe, for example, X:Y, where X corresponds to hydrogen (e.g., 3 forammonia reforming) and Y corresponds to nitrogen (e.g., 1 for ammoniareforming) in volume, mole, or partial pressure basis ratio, and where Xand Y are any integer greater than or equal to 1. The reformate gasesmay comprise one or more gases constituting the exit flow from areformer (or any components or subcomponents thereof). The reformer maycomprise an ammonia reformer for catalytically decomposing ammonia. Thecatalytic decomposition of ammonia may be driven using a heat source.The heat source may comprise one or more combustors and/or one or moreelectrical heaters. The one or more combustors may be configured tocombust hydrogen, ammonia, one or more hydrocarbons, or any combinationthereof to generate thermal energy. The one or more electrical heatersmay be configured to covert electrical energy to thermal energy viajoule heating mechanism. The thermal energy may be used to drive thecatalytic decomposition of ammonia.

Channel Features

The one or more features can comprise various dimensions, shapes, andorientations. In some cases, the one or more features can comprise oneor more cuts, one or more cutouts, one or more grooves, or anycombination thereof. In some cases, a cut can be an incision or slit inan anode channel. In some cases, a cut may comprise removal of asubstantially minor amount of material (e.g., zero material or close tozero material by weight, for example, less than about 1 to 3% by weight)from the anode channel. A cutout can be an opening in an anode channel.A cutout can comprise removal of a substantial amount of material fromthe anode channel. A groove can be a recess or trench in the anodechannel comprising a depth that does not extend through the entirethickness of the anode channel. A groove can comprise removal of asubstantial amount of material from the anode channel. A groove cancomprise removal of a substantially minor amount of material from theanode channel.

The one or more features can comprise various depths. The one or morefeatures can comprise a depth less than 5, 4, 3, 2, 1, 0.9, 0.8, 0.7,0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03,0.02, or 0.01 mm. The one or more features can comprise a depth greaterthan 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09,0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01 mm. The depth of theone or more features may be construed with respect to a thickness of theGDL. In some cases, the depth is at least 1/32, 1/16, ⅛, ¼, ½, ¾, ⅞,15/16, or 31/32 of the thickness of the GDL. In some cases, the depth isat most 1/32, 1/16, ⅛, ¼, ½, ¾, ⅞, 15/16, or 31/32 of the thickness ofthe GDL.

The one or more features can comprise various surface areas. The one ormore features can extend across a portion of the surface of the anodechannel. In some cases, a ratio of a projected surface area of the oneor more features to a projected surface area of the anode channel is atleast 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, theratio of a projected surface area of the one or more features to aprojected surface area of the anode channel is at most 0.1, 0.2, 0.3,0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

The one or more features can comprise any number of features. In somecases, the one or more features can comprise two or more features. Theone or more features can comprise at least 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 features. The one or morefeatures can comprise at most 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40,50, 60, 70, 80, 90, or 100 features.

The one or more features can comprise various orientations. In somecases, at least a first segment of a first feature in two or morefeatures is substantially parallel to a second segment of a secondfeature of the two or more features. In some cases, at least a firstsegment of a first feature in two or more features is substantiallyperpendicular to a second segment of a second feature of the two or morefeatures. In some cases, at least a first segment of a first feature intwo or more features is at an angle to a second segment of a secondfeature of the two or more features, wherein the angle is between 0 and90 degrees, between 0 and 30 degrees, between 15 and 75 degrees, orbetween 30 and 60 degrees. In some cases, two or more features can beconnected or disconnected. In some cases, two or more features canintersect. A feature can be substantially parallel with the longest sideof the anode channel. A feature can be substantially parallel with theshortest side of the anode channel. The one or more features cancomprise various shapes. For example, the one or more features cancomprise a substantially straight shape, a curved shape, a serpentineshape, or another shape.

FIG. 11 schematically illustrates various examples of cut configurationsthat may be utilized for an anode channel of a fuel cell. The cutconfigurations may comprise a plurality of cuts across a surface of theanode channel of the fuel cell. The plurality of cuts may comprise oneor more cuts into the surface of the anode channel to reduce the buildupof nitrogen in the anode and facilitate the outflow of nitrogen from thefuel cell so that the nitrogen does not accumulate in the gas diffusionlayer of the anode. It is noted herein that the expression “anodechannel” may be construed as an “anode gas diffusion layer channel,” an“anode current collecting layer channel,” or a combination of both.

The cuts may comprise a depth extending into the anode channel rangingfrom about 0.01 millimeters to about 10 mm. In some embodiments, thedepth is at least about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm,about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm,about 10 mm, or any value therebetween. In some embodiments, the depthis at most about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2 mm,about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm,about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm, about 4mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10mm, or any value therebetween. In some embodiments, the depth is between0.01 mm and about 10 mm, between about 0.05 mm and about 9 mm, betweenabout 0.1 mm and about 8 mm, between 0.2 mm and about 7 mm, betweenabout 0.3 mm and about 6 mm, between about 0.4 mm and about 5 mm,between 0.5 mm and about 4 mm, between about 0.6 mm and about 3 mm,between about 0.7 mm and about 2 mm, between 0.8 mm and about 1 mm, orbetween about 0.9 mm and about 10 mm. In some embodiments, the one ormore cuts may comprise depths extending into the anode channel equal tothe thickness of the anode channel.

In some embodiments, the one or more cuts may extend into the anodechannel at a depth ranging from about ⅛ to about ½ of the thickness ofthe anode channel. In some embodiments, the depth is at least about ⅛,about 1/7, about ⅙, about ⅕, about ¼, about ⅓, about ½, of the thicknessof the anode channel, or any value therebetween. In some embodiments,the depth is at most about ⅛, about 1/7, about ⅙, about ⅕, about ¼,about ⅓, about ½, of the thickness of the anode channel, or any valuetherebetween. In some embodiments, the depth is between ⅛ and about ½,between about 1/7 and about ⅓, between about ⅙ and about ¼, or between ⅕and about ½ of the thickness of the anode channel. For example, in ananode channel comprising a thickness of 2 mm, the cuts may comprise adepth ranging from about 0.25 mm to about 1 mm.

In some embodiments, the one or more cuts may extend into the anodechannel at a depth ranging from about ½ to about ⅘ of the thickness ofthe anode channel. In some embodiments, the depth is at least about ½,about ⅔, about ¾, about ⅘, of the thickness of the anode channel, or anyvalue therebetween. In some embodiments, the depth is at most about ½,about ⅔, about ¾, about ⅘, of the thickness of the anode channel, or anyvalue therebetween. In some embodiments, the depth is between ½ andabout ⅘, between about ⅔ and about ¾, or between about ¾ and about ⅘ ofthe thickness of the anode channel. For example, in an anode channelcomprising a thickness of 2 mm, the cuts may comprise a depth rangingfrom about 1 mm to about 1.6 mm.

In some cases, some of the one or more cuts may extend into the anodechannel at a different depth than others of the one or more cuts (e.g.,a first set of cuts may comprise a depth of 0.25 mm and a second set ofcuts may comprise a depth of 0.5 mm). In some cases, each of the one ormore cuts may extend into the anode channel at the same depth.

In some cases, the fuel cell comprises an anode gas diffusion layer withone or more anode channels. In some embodiments, the one or more anodechannels comprise one or more features. In some embodiments, the one ormore features comprise (i) one or more cuts or grooves or (ii) one ormore cutouts or openings configured to enhance diffusion and transportof the source material through the anode gas diffusion layer. In someembodiments, the one or more features are configured to direct a flow ofnitrogen from the anode gas diffusion layer to out of the fuel cell sothat nitrogen does not accumulate in the anode gas diffusion layer.

In some embodiments, a feature of the one or more features has a depththat is at least about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm,about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm,about 10 mm, or any value therebetween. In some embodiments, the depthis at most about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2 mm,about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm,about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm, about 4mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10mm, or any value therebetween. In some embodiments, the depth is between0.01 mm and about 10 mm, between about 0.05 mm and about 9 mm, betweenabout 0.1 mm and about 8 mm, between 0.2 mm and about 7 mm, betweenabout 0.3 mm and about 6 mm, between about 0.4 mm and about 5 mm,between 0.5 mm and about 4 mm, between about 0.6 mm and about 3 mm,between about 0.7 mm and about 2 mm, between 0.8 mm and about 1 mm, orbetween about 0.9 mm and about 10 mm.

In some cases, the cut configurations may comprise one or more cutsextending across at least a portion of the surface of the anode channel.In some cases, the one or more cuts may be parallel to each other. Inother cases, the one or more cuts may not or need not be parallel toeach other. In some cases, the cuts may comprise one or more horizontalcuts extending along a width of the anode channel and/or one or morevertical cuts extending along a length of the anode channel. The one ormore horizontal cuts and the one or more vertical cuts may or may notintersect with each other. In some cases, the surface of the anodechannel may comprise one or more sets of cut configurations. The one ormore sets of cut configurations may be located on different portions orregions of the surface of the anode channel. In some cases, the one ormore sets of cut configurations may be distributed across differentquadrants of the surface of the anode channel. In some cases, the one ormore cuts may be disposed at an angle relative to each other. In somecases, the one or more cuts may be disposed at a plurality of differentangles relative to each other.

FIG. 12 schematically illustrates various examples of cutoutconfigurations that may be utilized for an anode channel of a fuel cell.The cutout configurations may comprise a plurality of cutouts (e.g.,openings) across a surface of the anode channel of the fuel cell. Theplurality of cutouts may comprise one or more cutouts in the surface ofthe anode channel to reduce the buildup of nitrogen in the anode andfacilitate the outflow of nitrogen from the fuel cell so that thenitrogen does not accumulate in the gas diffusion layer of the anode. Insome cases, a cutout area ratio (a ratio of (i) the removed area of thecutout to (ii) the original area of the surface of the anode channel;e.g., if 20% of the original area of the surface is removed, the cutoutarea ratio may be 0.2) may range from about 0.01 to about 0.5. In somecases, the cutout area ratio may range from about 0.3 to about 0.7. Insome cases, the cutout area ratio may range from about 0.5 to about 0.9.In some embodiments, the cutout area ratio is at least about 0.01, about0.05, about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6,about 0.7, about 0.8, about 0.9, or any value therebetween. In someembodiments, the cutout area ratio is at most about 0.01, about 0.05,about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about0.7, about 0.8, about 0.9, or any value therebetween. In someembodiments, the cutout area ratio is between 0.01 and about 0.9,between about 0.05 and about 0.8, between about 0.1 and about 0.7,between 0.2 and about 0.6, between about 0.3 and about 0.5, or betweenabout 0.4 and about 0.9.

In some cases, the cutout configurations may comprise one or morecutouts extending across at least a portion of the surface of the anodechannel. In some cases, the one or more cutouts may be parallel to eachother. In other cases, the one or more cutouts may not or need not beparallel to each other. In some cases, the cutouts may comprise one ormore horizontal cutouts extending along a width of the anode channeland/or one or more vertical cutouts extending along a length of theanode channel. The one or more horizontal cutouts and the one or morevertical cutouts may or may not intersect with each other. In somecases, the surface of the anode channel may comprise one or more sets ofcutout configurations. The one or more sets of cutout configurations maybe located on different portions or regions of the surface of the anodechannel. In some cases, the one or more sets of cutout configurationsmay be distributed across different quadrants of the surface of theanode channel. In some cases, the one or more cutouts may be disposed atan angle relative to each other. In some cases, the one or more cutoutsmay be disposed at a plurality of different angles relative to eachother.

In some embodiments, one or more grooves may extend into the anodechannel at a depth ranging from about ⅛ to about ½ of the thickness ofthe anode channel. In some embodiments, the depth is at least about ⅛,about 1/7, about ⅙, about ⅕, about ¼, about ⅓, about ½, of the thicknessof the anode channel, or any value therebetween. In some embodiments,the depth is at most about ⅛, about 1/7, about ⅙, about ⅕, about ¼,about ⅓, about ½, of the thickness of the anode channel, or any valuetherebetween. In some embodiments, the depth is between ⅛ and about ½,between about 1/7 and about ⅓, between about ⅙ and about ¼, or between ⅕and about ½ of the thickness of the anode channel. For example, in ananode channel comprising a depth of 2 mm, the grooves may comprise adepth ranging from about 0.25 mm to about 1 mm. In some embodiments theone or more grooves may extend into the anode channel at a depth rangingfrom about ½ to about ⅘ of the thickness of the anode channel. In someembodiments, the depth is at least about ½, about ⅔, about ¾, about ⅘,of the thickness of the anode channel, or any value therebetween. Insome embodiments, the depth is at most about ½, about ⅔, about ¾, about⅘, of the thickness of the anode channel, or any value therebetween. Insome embodiments, the depth is between ½ and about ⅘, between about ⅔and about ¾, or between about ¾ and about ⅘ of the thickness of theanode channel.

In some cases, the one or more grooves may extend into the anode channelat a depth that is different from the thickness of the anode channel.For example, in an anode channel comprising a depth of 2 mm, the groovesmay comprise a depth ranging from about 1 mm to about 1.6 mm. In somecases, the one or more grooves may extend into the anode channel at adepth that is equal to the thickness of the anode channel. In somecases, a groove area ratio (the ratio of the area of the groove to theoriginal area of the surface of the anode channel; e.g., if 20% of theoriginal area comprises grooves, the groove area ratio may be 0.2) mayrange from about 0.01 to about 0.5. In some cases, the groove area ratiomay range from about 0.3 to about 0.7. In some cases, the groove arearatio may range from about 0.5 to about 0.9. In some embodiments, thegroove area ratio is at least about 0.01, about 0.05, about 0.1, about0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8,about 0.9, or any value therebetween. In some embodiments, the groovearea ratio is at most about 0.01, about 0.05, about 0.1, about 0.2,about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about0.9, or any value therebetween. In some embodiments, the groove arearatio is between 0.01 and about 0.9, between about 0.05 and about 0.8,between about 0.1 and about 0.7, between 0.2 and about 0.6, betweenabout 0.3 and about 0.5, or between about 0.4 and about 0.9.

In some cases, the anode channel may comprise one or more cuts extendingacross at least a portion of the surface of the anode channel, one ormore cutouts extending across at least a portion of the surface of theanode channel, one or more grooves extending across at least a portionof the surface of the anode channel, or any combination of cuts, cutoutsand grooves.

In some cases, cuts may be preferred when a minimal cutout area ratio ispreferred. In some cases, cutouts or grooves, or a combination thereof,may be preferred to achieve a higher rate of nitrogen purging (e.g., incomparison to cuts alone, which may achieve a relatively lower rate ofnitrogen purging).

In some cases, combinations of one or more cuts, one or more cutouts, orone or more grooves may be employed when minimal cutout area ratios orminimal groove area ratios are preferred. In some cases, the minimalcutout area ratio or groove area ratio may be less than 0.1. In somecases, the minimal cutout or groove area ratio may be less than 0.2. Insome cases, the minimal cutout or groove area ratio may be less than0.5.

In some cases, the anode channel may include both cuts and cutouts thatextend into the anode channel at the same depth. In some cases, theanode channel may include both cuts and cutouts that extend into theanode channel at different depths.

In some cases, the cuts, cutouts, and grooves may be manufactured usingone or more methods comprising at least one of stamping, laser cutting,engraving, chemical etching, and embossing. In some cases, the materialremoved by the cutouts may be recycled and used to form one or morechannels in the one or more fuel cells.

In some cases, the fuel cell comprises a plurality of channels in fluidcommunication with the anode. The plurality of channels can be stackedin layers that are adjacent to one another. FIG. 6 schematicallyillustrates various examples of multi-layer anode channel designs thatcan be implemented to enhance fuel cell performance when the fuel cellis used to process a gaseous mixture of hydrogen and nitrogen togenerate electrical energy. The multi-layer anode channel may comprise aplurality of layers. The plurality of layers may comprise at least afirst layer and a second layer. At least one of the first layer and thesecond layer may comprise one or more cuts and/or one or more cutouts.In some cases, a first layer of the plurality of layers may not have anycuts or cutouts. In such cases, a second layer of the plurality oflayers may comprise one or more cuts and/or one or more cutouts. In somecases, each of the first layer and the second layer may comprise one ormore cuts and/or one or more cutouts. The cuts or cutouts of the firstlayer may or may not be aligned with the cuts or cutouts of the secondlayer. In some cases, the first layer may comprise a first set of cutsor cutouts and the second layer may comprise a second set of cuts orcutouts. The first and second sets of cuts or cutouts may or may notoverlap each other. In some cases, the first and second sets of cuts orcutouts may comprise different patterns of cuts or cutouts. In somecases, the first and second sets of cuts or cutouts may comprise acombination of horizontal and vertical cuts or cutouts. In some cases,the first set of cuts or cutouts may comprise a plurality of horizontalcuts or cutouts, and the second set of cuts or cutouts may comprise aplurality of vertical cuts or cutouts. In some cases, the first set ofcuts or cutouts may comprise a plurality of vertical cuts or cutouts,and the second set of cuts or cutouts may comprise a plurality ofhorizontal cuts or cutouts. At least one channel of the plurality ofchannels may not comprise (i.e., may lack) the one or more featurescomprising cuts, cutouts, and/or grooves.

As described above, in some cases, the one or more cuts and/or the oneor more cutouts may extend across at least a portion of the surface ofthe anode channel. In some cases, the one or more cuts and/or the one ormore cutouts may be parallel to each other. In other cases, the one ormore cuts and/or the one or more cutouts may not or need not be parallelto each other. In some cases, the one or more cuts and/or the one ormore cutouts may comprise one or more horizontal cuts or cutoutsextending along a width of the anode channel and/or one or more verticalcuts or cutouts extending along a length of the anode channel. The oneor more horizontal cuts or cutouts and the one or more vertical cuts orcutouts may or may not intersect with each other. In some cases, thesurface of the anode channel may comprise one or more sets of cutconfigurations or cutout configurations. The one or more sets of cutconfigurations or cutout configurations may be located on differentportions or regions of the surface of the anode channel. In some cases,the one or more sets of cut configurations or cutout configurations maybe distributed across different quadrants of the surface of the anodechannel. In some cases, the one or more cuts or cutouts may be disposedat an angle relative to each other. In some cases, the one or more cutsor cutouts may be disposed at a plurality of different angles relativeto each other. In some cases, the one or more surface features maycomprise one or more cuts or grooves on a surface of the one or moreanode channels. The one or more cuts or grooves may extend across aportion of the surface of the one or more anode channels. In some cases,the one or more cuts or grooves may comprise two or more cuts or groovesthat are parallel to each other. In other cases, the one or more cuts orgrooves may comprise two or more cuts or grooves that are perpendicularto each other. In some cases, the one or more cuts or grooves maycomprise two or more cuts or grooves that are disposed at an anglerelative to each other. The angle may range from 0 degrees to about 90degrees. In some cases, the angle may range from 0 degrees to about 45degrees. In some cases, the angle may range from 0 degrees to about 30degrees. In some cases, the angle may range from 0 degrees to about 15degrees. In some cases, the one or more cuts or grooves may comprise twoor more cuts or grooves that intersect with each other. In other cases,the one or more cuts or grooves may comprise two or more cuts or groovesthat do not intersect.

In some cases, the one or more surface features may comprise one or morecutouts or openings on a surface of the one or more channels. The one ormore cutouts or openings may extend across a portion of the surface ofthe one or more channels. In some cases, the one or more cutouts oropenings may comprise two or more cutouts or openings that are parallelto each other. In other cases, the one or more cutouts or openings maycomprise two or more cutouts or openings that are perpendicular to eachother. In some cases, the one or more cutouts or openings may comprisetwo or more cutouts or openings that are disposed at an angle relativeto each other. The angle may range from 0 degrees to about 90 degrees.In some cases, the angle may range from 0 degrees to about 45 degrees.In some cases, the angle may range from 0 degrees to about 30 degrees.In some cases, the angle may range from 0 degrees to about 15 degrees.In some cases, the one or more cutouts or openings may comprise two ormore cuts or grooves that intersect with each other. In other cases, theone or more cutouts or openings may comprise two or more cutouts oropenings that do not intersect.

In some embodiments, the gas diffusion layer of the anode may compriseone or more layers. In some cases, the one or more layers may comprisetwo or more layers. At least one layer of the two or more layers maycomprise the one or more surface features. The one or more surfacefeatures may comprise (i) one or more cuts or grooves and/or (ii) one ormore cutouts or openings. In some cases, the two or more layers maycomprise a first layer comprising a first set of surface features and asecond layer comprising a second set of surface features. In some cases,the first set of features and the second set of features may comprise asame or similar set of features. In other cases, the first set offeatures and the second set of features may comprise different sets offeatures. In some cases, the first set of features and the second set offeatures may overlap or partially overlap. In other cases, the first setof features and the second set of features may not or need not overlap.

In some cases, the anode gas diffusion layer may comprise a felt, afoam, a cloth, or a paper material. The felt, the foam, cloth, or thepaper material may comprise, for example, graphite or anothercarbon-based material (e.g., carbon fibers). In some cases, the felt,the foam, the cloth, or the paper material may comprise a carbon felt,which may have similar features, properties, or characteristics with acotton material. Alternatively, the felt, the foam, the cloth, or thepaper material may comprise a carbon paper, which may have similarfeatures, properties, or characteristics to with a sheet of paper. Insome cases, the felt, the foam, the cloth, or the paper material maycomprise polytetrafluoroethylene (PTFE)-based material. In some cases,the felt, the foam, the cloth, or the paper material may comprise bothcarbon-based material and PTFE-based material. In some cases, the felt,the foam, the cloth, or the paper material may comprise hydrophobicproperties with a water contact angle greater than about 90 degrees. Insome cases, the felt, the foam, the cloth, or the paper material maycomprise hydrophilic properties with a water contact angle less thanabout 90 degrees. In some cases, at least one part of the felt, thefoam, the cloth, or the paper material may comprise hydrophobicproperties and at least one other part of the felt, the foam, the cloth,or the paper material may comprise hydrophilic properties. The felt,foam, cloth, or paper materials may be porous, and may comprisedifferent properties such as porosity, pore sizes, density, brittleness,and flexibility. In some cases, the felt, the foam, the cloth, or thepaper material may conduct electrical currents. In some cases, the felt,the foam, the cloth, or the paper material may comprise at least one ofsurface texture, porosity, or pore size that is different between afirst side and a second side. In some cases, the first side is front ortop side and the second side is bottom or back side. In some cases, thefirst side faces the electrolyte and the second side faces the outsideof the fuel cell. In some instances, a denser material may providebetter performance for the anode gas diffusion layer. In some instances,a material that is too dense may increase gas diffusion or transportresistance. In some instances, a thinner material may provide betterperformance for the anode gas diffusion layer by decreasing gasdiffusion or transport resistance. In some instances, a thinner materialis preferred to increase the power density of the fuel cell. In someinstances, a material that is too thin may increase gas diffusion ortransport resistances. It is noted herein that the anode diffusion layermay comprise materials that are not felt, foam, paper, cloth,carbon-based materials, or PTFE-based material.

In cases where a single layer design is utilized, the material for thegas diffusion layer may need to be porous in order to diffuse hydrogenthrough the gas diffusion layer. In cases where a multi-layer design isutilized, the membrane side of the gas diffusion layer may comprise aporous sheet material and the current collecting side (where thechannels are placed) may comprise any current conducting sheet material,such as a metal, copper, nickel, zinc, platinum, aluminum, steel,titanium, gold, or carbon-based material. In some cases, currentconducting sheet may comprise any current conducting sheet material withone or more coatings of different current conducting materials.

In some cases, the felt, the foam, the cloth, or the paper material maycomprise a carbon paper. The carbon paper may be manufactured by burninga carbon-based polymer sheet. The carbon felt, foam, cloth, or papermaterial may not or need not comprise a crystalline structure.

Fuel Cell Exit Flow

In some cases, exit flows may exit one or more fuel cells. The exit flowfrom the fuel cells may comprise H₂, N₂, O₂, and/or one or more reactionbyproducts (e.g., water). An exit flow from the anode channel cancomprise H₂, N₂, ammonia (e.g., trace ammonia from ammonia reforming),water, or any combination thereof. An exit flow from the cathode channelcan comprise O₂, N₂, water, or any combination thereof. In some cases,the fuel cell exit flow may comprise unconverted hydrogen from the fuelcells (hydrogen that is not consumed by the fuel cell and that is notconverted into protons and electrons at the electrolyte membrane). Insome cases, the fuel cell exit flow may comprise unconverted hydrogenfrom the exit flow of the anode channel of the fuel cells (an anodeoffgas). In some cases, the unconverted hydrogen may be directed back tothe one or more reactors for combustion heating to heat the reactors forfurther ammonia decomposition. In some cases, the fuel cell exit flowmay comprise unconverted hydrogen from the fuel cells, unconvertedammonia from the reactors, or unadsorbed ammonia from the adsorptiontowers. In some cases, the unconverted hydrogen from the fuel cells andthe unconverted or unadsorbed ammonia from the reactors or theadsorption towers may be directed back to the one or more reactors forcombustion heating to heat the reactors for further ammoniadecomposition. In some cases, the unconverted O₂ from the exit flow ofthe cathode channel may be directed to the one or more reactors forcombustion heating to heat the reactors for ammonia decomposition.

In some cases, a stream exiting one or more fuel cells may comprise avolume fraction, a molar fraction, or a partial pressure fraction ofhydrogen at most about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006,0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007,0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1,0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, a streamexiting one or more fuel cells may comprise a volume fraction, a molarfraction, or a partial pressure fraction of hydrogen ranging from atleast about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007,0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008,0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2,0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, a stream exitingone or more fuel cells may comprise a volume fraction, a molar fraction,or a partial pressure fraction of hydrogen ranging from 0.5 to 0.8. Insome cases, a stream exiting one or more fuel cells may comprise avolume fraction, a molar fraction, or a partial pressure fraction ofhydrogen ranging from 0.4 to 0.7. In some cases, a stream exiting one ormore fuel cells may comprise a volume fraction, a molar fraction, or apartial pressure fraction of hydrogen ranging from 0.3 to 0.6. In somecases, a stream exiting one or more fuel cells may comprise a volumefraction, a molar fraction, or a partial pressure fraction of hydrogenranging from 0.2 to 0.5. In some cases, a stream exiting one or morefuel cells may comprise a volume fraction, a molar fraction, or apartial pressure fraction of hydrogen ranging from 0.1 to 0.4. In somecases, a stream exiting one or more fuel cells may comprise a volumefraction, a molar fraction, or a partial pressure fraction of hydrogenranging from 0.05 to 0.3. In some cases, a stream exiting one or morefuel cells may comprise a volume fraction, a molar fraction, or apartial pressure fraction of hydrogen ranging from 0.3 to 0.4.

In some cases, a stream exiting one or more fuel cells may comprise avolume fraction, a molar fraction, or a partial pressure fraction ofnitrogen ranging from at most about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06,0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.91,0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.991, 0.992, 0.993,0.994, 0.995, 0.996, 0.997, 0.998, or 0.999. In some cases, a streamexiting one or more fuel cells may comprise a volume fraction, a molarfraction, or a partial pressure fraction of nitrogen ranging from atleast about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007,0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008,0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2,0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96,0.97, 0.98, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997,0.998, or 0.999. In some cases, a stream exiting one or more fuel cellsmay comprise a volume fraction, a molar fraction, or a partial pressurefraction of nitrogen ranging from 0.1 to 0.4. In some cases, a streamexiting one or more fuel cells may comprise a volume fraction, a molarfraction, or a partial pressure fraction of nitrogen ranging from 0.3 to0.6. In some cases, a stream exiting one or more fuel cells may comprisea volume fraction, a molar fraction, or a partial pressure fraction ofnitrogen ranging from 0.5 to 0.8. In some cases, a stream exiting one ormore fuel cells may comprise a volume fraction, a molar fraction, or apartial pressure fraction of nitrogen ranging from 0.6 to 0.9. In somecases, a stream exiting one or more fuel cells may comprise a volumefraction, a molar fraction, or a partial pressure fraction of nitrogenranging from 0.4 to 0.6. In some cases, a stream exiting one or morefuel cells may comprise at least two of hydrogen, nitrogen, water, oroxygen.

In some cases, a stream exiting one or more fuel cells may comprise avolume fraction, a molar fraction, or a partial pressure fraction ofammonia ranging from at most about 0.0001, 0.0002, 0.0003, 0.0004,0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004,0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06,0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. Insome cases, a stream exiting one or more fuel cells may comprise avolume fraction, a molar fraction, or a partial pressure fraction ofammonia ranging from at least about 0.0001, 0.0002, 0.0003, 0.0004,0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004,0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06,0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

In some cases, a plurality of streams comprising unconverted hydrogenmay exit from the one or more fuel cells, one or more fuel cell stacks,or one or more fuel cell modules. In some cases, the plurality ofstreams exiting from the one or more fuel cells, one or more fuel cellstacks, or one or more fuel cell modules may be directed to the one ormore combustion heaters of the ammonia reformer. In some cases, theplurality of streams exiting from the one or more fuel cells, one ormore fuel cell stacks, or one or more fuel cell modules have at leastone stream that is different in flow rate, hydrogen mole fraction,nitrogen mole fraction, or water mole fraction from the other exitstreams. In some cases, a plurality of streams exit from the one or morefuel cells, one or more fuel cell stacks, one or more fuel cell modulescomprise flow rates within a selected tolerance based on a target flowrate (e.g., target flow rate to a single fuel cell, fuel cell stack, orfuel cell module). In some cases, the selected tolerance is at leastabout 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, or 500%.In some cases, the selected tolerance is at most about 10, 20, 30, 40,50, 60, 70, 80, 90, 100, 200, 300, 400, or 500%.

In some cases, one or more streams exiting the one or more fuel cells,one or more fuel cell stacks, or one or more fuel cell modules may passthrough one or more water collectors or condensers. In some cases, theone or more water collectors or condensers remove at least portion ofwater in the one or more streams exiting the one or more fuel cells, oneor more fuel cell stacks, or one or more fuel cell modules. In somecases, the one or more water collectors or condensers remove at leastportion of water in the one or more streams exiting the one or more fuelcells, one or more fuel cell stacks, or one or more fuel cell modulesbefore providing the one or more streams exiting the one or more fuelcells, one or more fuel cell stacks, or one or more fuel cell modules tothe one or more combustion heaters of the ammonia reformer. In somecases, the one or more streams exiting the one or more fuel cells, oneor more fuel cell stacks, or one or more fuel cell modules comprise H₂,N₂, water, or O₂.

Computer Systems

In an aspect, the present disclosure provides computer systems that areprogrammed or otherwise configured to implement methods of thedisclosure. FIG. 14 shows a computer system 1401 that is programmed orotherwise configured to implement a method for processing hydrogenand/or mixtures of hydrogen and nitrogen. In some embodiments, thecomputer system is configured to operate the fuel cell to allow purgingof nitrogen from the fuel cell while the fuel cell is generatingelectricity. In some embodiments, the computer system is configured tooperate the fuel cell to allow continuous purging of nitrogen. Thecomputer system 1401 may be configured to, for example, (i) control aflow of a source material comprising hydrogen and nitrogen to one ormore fuel cells and (ii) control an operation of the one or more fuelcells to process the source material to generate electricity (e.g., anelectrical current). The computer system 1401 can be an electronicdevice of a user or a computer system that is remotely located withrespect to the electronic device. The electronic device can be a mobileelectronic device.

The computer system 1401 may include a central processing unit (CPU,also “processor” and “computer processor” herein) 1405, which can be asingle core or multi core processor, or a plurality of processors forparallel processing. The computer system 1401 also includes memory ormemory location 1410 (e.g., random-access memory, read-only memory,flash memory), electronic storage unit 1415 (e.g., hard disk),communication interface 1420 (e.g., network adapter) for communicatingwith one or more other systems, and peripheral devices 1425, such ascache, other memory, data storage and/or electronic display adapters.The memory 1410, storage unit 1415, interface 1420 and peripheraldevices 1425 are in communication with the CPU 1405 through acommunication bus (solid lines), such as a motherboard. The storage unit1415 can be a data storage unit (or data repository) for storing data.The computer system 1401 can be operatively coupled to a computernetwork (“network”) 1430 with the aid of the communication interface1420. The network 1430 can be the Internet, an internet and/or extranet,or an intranet and/or extranet that is in communication with theInternet. The network 1430 in some cases is a telecommunication and/ordata network. The network 1430 can include one or more computer servers,which can enable distributed computing, such as cloud computing. Thenetwork 1430, in some cases with the aid of the computer system 1401,can implement a peer-to-peer network, which may enable devices coupledto the computer system 1401 to behave as a client or a server.

The CPU 1405 can execute a sequence of machine-readable instructions,which can be embodied in a program or software. The instructions may bestored in a memory location, such as the memory 1410. The instructionscan be directed to the CPU 1405, which can subsequently program orotherwise configure the CPU 1405 to implement methods of the presentdisclosure. Examples of operations performed by the CPU 1405 can includefetch, decode, execute, and writeback.

The CPU 1405 can be part of a circuit, such as an integrated circuit.One or more other components of the system 1401 can be included in thecircuit. In some cases, the circuit is an application specificintegrated circuit (ASIC).

The storage unit 1415 can store files, such as drivers, libraries andsaved programs. The storage unit 1415 can store user data, e.g., userpreferences and user programs. The computer system 1401 in some casescan include one or more additional data storage units that are locatedexternal to the computer system 1401 (e.g., on a remote server that isin communication with the computer system 1401 through an intranet orthe Internet).

The computer system 1401 can communicate with one or more remotecomputer systems through the network 1430. For instance, the computersystem 1401 can communicate with a remote computer system of a user(e.g., an individual operating a reactor from which the source materialcomprising hydrogen and nitrogen is produced, an entity monitoring theoperation of the reactor or one or more fuel cells operatively coupledto the reactor, or an end user operating a device or a vehicle that canbe powered using electrical energy derived or produced from the sourcematerial using the one or more fuel cells). Examples of remote computersystems include personal computers (e.g., portable PC), slate or tabletPC's (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones(e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personaldigital assistants. The user can access the computer system 1401 via thenetwork 1430.

Methods as described herein can be implemented by way of machine (e.g.,computer processor) executable code stored on an electronic storagelocation of the computer system 1401, such as, for example, on thememory 1410 or electronic storage unit 1415. The machine executable ormachine readable code can be provided in the form of software. Duringuse, the code can be executed by the processor 1405. In some cases, thecode can be retrieved from the storage unit 1415 and stored on thememory 1410 for ready access by the processor 1405. In some situations,the electronic storage unit 1415 can be precluded, andmachine-executable instructions are stored on memory 1410.

The code can be pre-compiled and configured for use with a machinehaving a processor adapted to execute the code, or can be compiledduring runtime. The code can be supplied in a programming language thatcan be selected to enable the code to execute in a pre-compiled oras-compiled fashion.

Aspects of the systems and methods provided herein, such as the computersystem 1401, can be embodied in programming. Various aspects of thetechnology may be thought of as “products” or “articles of manufacture”typically in the form of machine (or processor) executable code and/orassociated data that is carried on or embodied in a type of machinereadable medium. Machine-executable code can be stored on an electronicstorage unit, such as memory (e.g., read-only memory, random-accessmemory, flash memory) or a hard disk. “Storage” type media can includeany or all of the tangible memory of the computers, processors or thelike, or associated modules thereof, such as various semiconductormemories, tape drives, disk drives and the like, which may providenon-transitory storage at any time for the software programming. All orportions of the software may at times be communicated through theInternet or various other telecommunication networks. Suchcommunications, for example, may enable loading of the software from onecomputer or processor into another, for example, from a managementserver or host computer into the computer platform of an applicationserver. Thus, another type of media that may bear the software elementsincludes optical, electrical and electromagnetic waves, such as usedacross physical interfaces between local devices, through wired andoptical landline networks and over various air-links. The physicalelements that carry such waves, such as wired or wireless links, opticallinks or the like, also may be considered as media bearing the software.As used herein, unless restricted to non-transitory, tangible “storage”media, terms such as computer or machine “readable medium” refer to anymedium that participates in providing instructions to a processor forexecution.

Hence, a machine readable medium, such as computer-executable code, maytake many forms, including but not limited to, a tangible storagemedium, a carrier wave medium or physical transmission medium.Non-volatile storage media including, for example, optical or magneticdisks, or any storage devices in any computer(s) or the like, may beused to implement the databases, etc. shown in the drawings. Volatilestorage media include dynamic memory, such as main memory of such acomputer platform. Tangible transmission media include coaxial cables;copper wire and fiber optics, including the wires that comprise a buswithin a computer system. Carrier-wave transmission media may take theform of electric or electromagnetic signals, or acoustic or light wavessuch as those generated during radio frequency (RF) and infrared (IR)data communications. Common forms of computer-readable media thereforeinclude for example: a floppy disk, a flexible disk, hard disk, magnetictape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any otheroptical medium, punch cards paper tape, any other physical storagemedium with patterns of holes, a RAM, a ROM, a PROM and EPROM, aFLASH-EPROM, any other memory chip or cartridge, a carrier wavetransporting data or instructions, cables or links transporting such acarrier wave, or any other medium from which a computer may readprogramming code and/or data. Many of these forms of computer readablemedia may be involved in carrying one or more sequences of one or moreinstructions to a processor for execution.

The computer system 1401 can include or be in communication with anelectronic display 1435 that comprises a user interface (UI) 1440 forproviding, for example, a portal for a user to monitor or track anoperation or a performance of the one or more fuel cells. In some cases,the performance of the one or more fuel cells may comprise, for example,a voltage of the electrical current generated using the one or more fuelcells. The portal may be provided through an application programminginterface (API). A user or entity can also interact with variouselements in the portal via the UI. Examples of UI's include, withoutlimitation, a graphical user interface (GUI) and web-based userinterface.

Methods and systems of the present disclosure can be implemented by wayof one or more algorithms. An algorithm can be implemented by way ofsoftware upon execution by the central processing unit 1405. Forexample, the algorithm may be configured to control an operation of theone or more fuel cells based on one or more sensor readings (e.g.,temperature measurements, flow rates, etc.), based on a power demand, orbased on a performance of the one or more fuel cells. The algorithm canbe configured to operate the fuel cell to allow purging of nitrogen fromthe fuel cell while the fuel cell is generating electricity, or tooperate the fuel cell to allow continuous purging of nitrogen.

Vehicles

In some cases, the one or more fuel cells may be adapted for use on anaerial vehicle. The aerial vehicle may comprise, for example, a mannedaerial vehicle, an unmanned aerial vehicle, or a drone. In some cases,the fuel cells may be integrated into a body of the aerial vehicle. Inother cases, the fuel cells may be placed on top of or underneath a bodyof the aerial vehicle. In some cases, the fuel cells may be electricallycoupled to a motor or an engine of the aerial vehicle.

In some cases, the one or more fuel cells may be adapted for use on aterrestrial vehicle, such as a car, a farming vehicle, or an automobile.The one or more fuel cells may be placed in or near a front portion ofthe terrestrial vehicle (e.g., in an engine bay of the vehicle). The oneor more fuel cells may be placed in or near an underside region of theterrestrial vehicle. The one or more fuel cells may be placed near arear end of the terrestrial vehicle. In some cases, the one or more fuelcells may be placed near an axle of the terrestrial vehicle (e.g., afront wheel axle and/or a rear wheel axle of the vehicle). In somecases, the fuel cells may be electrically coupled to a motor or anengine of the terrestrial vehicle.

In some cases, the one or more fuel cells may be adapted for use on aterrestrial vehicle, such as a truck or a semi-trailer truck. In somecases, the one or more fuel cells may be coupled to or integrated into arear portion of a tractor unit of the truck. The tractor unit (alsoknown as a prime mover, truck, semi-truck, semi-tractor, rig, big rig,or simply, a tractor) may comprise a heavy-duty towing engine thatprovides motive power for hauling a towed or trailered-load. In somecases, the one or more fuel cells may be positioned in or near a frontportion of the tractor unit (e.g., in the engine bay of the tractorunit). In other cases, the one or more fuel cells may be placed in ornear an underside region of the tractor unit. In some cases, theplurality of fuel cells may be distributed along the underside of thetractor unit. In some cases, one or more of the fuel cells may be placednear an axle (e.g., a front axle) of the tractor unit.

In some cases, the one or more fuel cells may be adapted for use in amarine vehicle. The marine vehicle may comprise, for example, a mannedmarine vehicle, an unmanned marine vehicle, a boat, or a ship. In somecases, the fuel cells may be integrated into a body of the marinevehicle. In other cases, the fuel cells may be placed on top of orunderneath a body of the marine vehicle. In some cases, the fuel cellsmay be electrically coupled to a motor or an engine of the marinevehicle. In some cases, the fuel cells may provide a back-up power ofthe marine vehicle. In some cases, the one or more fuel cells may beadapted for use in a submarine vehicle. In some cases, the fuel cellsmay be electrically coupled to a motor or an engine of the submarinevehicle.

In some cases, a vehicle may comprise a plurality of fuel cells. In somecases, the plurality of fuel cell modules may be positioned adjacent toeach other. In other cases, the plurality of fuel cell modules may belocated remote from each other (i.e., in or on different sides, regions,or sections of a vehicle). In some cases, the plurality of fuel cellmodules may be oriented in a same direction. In other cases, at leasttwo of the plurality of fuel cell modules may be oriented in differentdirections. In any of the embodiments described herein, the plurality offuel cell modules may be positioned and/or oriented appropriately tomaximize volumetric efficiency and minimize a physical footprint of theplurality of fuel cell modules. In any of the embodiments describedherein, the plurality of fuel cell modules may be positioned and/ororiented to conform with a size and/or a shape of the vehicle in or onwhich the fuel cell modules are placed or provided. In any of theembodiments described herein, the plurality of fuel cell modules may bepositioned and/or oriented to conform with a size and/or a shape of thevehicle to which the fuel cell modules are coupled or mounted.

In any of the embodiments described herein, the fuel cell modules may beplaced in or on different sides, regions, or sections of a vehicle. Thefuel cell modules may be positioned and/or oriented appropriately tomaximize volumetric efficiency and minimize a physical footprint of thefuel cell modules. The fuel cell modules may be positioned and/ororiented to conform with a size and/or a shape of the vehicle in or onwhich the fuel cell modules are placed or provided. The fuel cellmodules may be positioned and/or oriented to conform with a size and/ora shape of the vehicle to which the fuel cell modules are coupled ormounted.

Numbered Embodiments

Embodiment 1. A method for generating electricity using a fuel cell,comprising: reacting, using an ammonia reformer, ammonia to generate afirst continuous stream comprising nitrogen and hydrogen, wherein theammonia reformer is in fluid communication with the fuel cell, the fuelcell comprising: an electrochemical circuit comprising an anode, acathode, and an electrolyte between the anode and the cathode; a firstchannel comprising a first inlet and a first outlet, wherein the firstchannel is in fluid communication with the anode, wherein the firstchannel comprises one or more features configured to (i) increase ahydrogen consumption rate of the fuel cell, or (ii) increase an outputvoltage of the fuel cell at a same hydrogen consumption rate, when thefirst continuous stream contacts the anode compared to an equivalentfuel cell lacking the one or more features, wherein the one or morefeatures comprise (1) one or more cuts, (2) one or more cutouts, (3) oneor more grooves, or (4) any combination thereof, and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and directing thefirst continuous stream into the first channel via the first inlet sothat the hydrogen contacts the anode; directing a second continuousstream comprising oxygen into the second channel via the second inlet sothat the oxygen contacts the cathode; and reacting the hydrogen and theoxygen, using the fuel cell, to generate electrical power.

Embodiment 2. The method of embodiment 1, wherein the one or morefeatures increase the hydrogen consumption rate of the fuel cell whenthe first continuous stream contacts the anode compared to theequivalent fuel cell lacking the one or more features.

Embodiment 3. The method of embodiment 2, wherein the one or morefeatures increase the hydrogen consumption rate by at least 5, 10, 20,40, 60, 80, 100, 120, 140, 160, 180, or 200%.

Embodiment 4. The method of embodiment 2 or 3, wherein the one or morefeatures increase the hydrogen consumption rate by at most 5, 10, 20,40, 60, 80, 100, 120, 140, 160, 180, or 200%.

Embodiment 5. The method of any one of embodiments 1-4, wherein the oneor more features increase the output voltage at the same hydrogenconsumption rate when the first continuous stream contacts the anodecompared to the equivalent fuel cell lacking the one or more features.

Embodiment 6. The method of embodiment 5, wherein the one or morefeatures increase the voltage by at least 5, 10, 20, 40, 60, 80, 100,120, 140, 160, 180, or 200%.

Embodiment 7. The method of embodiment 5 or 6, wherein the one or morefeatures increase the hydrogen consumption rate by at most 5, 10, 20,40, 60, 80, 100, 120, 140, 160, 180, or 200%.

Embodiment 8. The method of any one of embodiments 1-7, wherein the oneor more features continuously purge nitrogen out of the fuel cell.

Embodiment 9. The method of embodiment 8, wherein the nitrogen iscontinuously purged out of the first channel by the one or more featuresso that nitrogen accumulation is reduced in the first channel, therebyincreasing the hydrogen consumption rate compared to the equivalent fuelcell lacking the one or more features.

Embodiment 10. The method of any one of embodiments 1-9, wherein thehydrogen consumption rate of the fuel cell when the first continuousstream contacts the anode is at least about 10, 20, 30, 40, 50, 60, 70,80, 90, or 99% of the hydrogen in the first continuous stream.

Embodiment 11. The method of any one of embodiments 1-10, wherein thehydrogen consumption rate of the fuel cell when the first continuousstream contacts the anode is at most about 10, 20, 30, 40, 50, 60, 70,80, 90, or 99% of the hydrogen in the first continuous stream.

Embodiment 12. The method of any one of embodiments 1-11, furthercomprising intermittently reducing the hydrogen consumption rate topurge out at least one of hydrogen, nitrogen, or water.

Embodiment 13. The method of any one of embodiments 1-12, furthercomprising reducing the hydrogen consumption rate and directing at leasta part of the first continuous stream to the ammonia reformer.

Embodiment 14. The method of any one of embodiments 1-13, furthercomprising reducing the hydrogen consumption rate of the fuel cell tozero and directing at least a part of the first continuous stream to theammonia reformer.

Embodiment 15. The method of embodiment 13 or 14, further comprisingflaring the at least the part of the first continuous stream directed tothe ammonia reformer at one or more combustion exhausts of one or morecombustion heaters, wherein the one or more combustion heaters are inoperable communication with the ammonia reformer for heating the ammoniareformer, and wherein the one or more combustion heaters are in fluidiccommunication with the fuel cell to receive the at least the part of thefirst continuous stream.

Embodiment 16. A method for generating electricity using a fuel cell,comprising: reacting, using an ammonia reformer, ammonia to generate afirst continuous stream comprising nitrogen and hydrogen, wherein theammonia reformer is in fluid communication with the fuel cell, the fuelcell comprising: an electrochemical circuit comprising an anode, acathode, and an electrolyte between the anode and the cathode; a firstchannel comprising a first inlet and a first outlet, wherein the firstchannel is in fluid communication with the anode, wherein the firstchannel comprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof; and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and directing thefirst continuous stream into the first channel via the first inlet sothat the hydrogen contacts the anode; directing a second continuousstream comprising oxygen into the second channel via the second inlet sothat the oxygen contacts the cathode; and reacting the hydrogen and theoxygen, using the fuel cell, to generate electrical power; wherein thefuel cell is configured to provide a ratio of an electrical power outputof the fuel cell to a projected surface area of the anode that is atleast about 0.05 W/cm² when the first continuous stream comprises about25% nitrogen and about 75% hydrogen by moles, and the second continuousstream comprises at least 20% oxygen by moles.

Embodiment 17. The method of embodiment 16, wherein the ratio is atleast about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4 W/cm².

Embodiment 18. The method of embodiment 16 or 17, wherein the ratio isat most about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4 W/cm².

Embodiment 19. The method of any one of embodiments 16-18, wherein theratio is based on the first continuous stream comprising a hydrogen flowrate of at least about 0.001, 0.01, 0.1, 1, 10, 100, 1000, 10000, or100000 mole per second.

Embodiment 20. The method of any one of embodiments 16-19, wherein theratio is based on the second continuous stream comprising an oxygen flowrate of at least about 0.0001, 0.001, 0.01, 0.1, 1, 10, 100, 1000,10000, 100000, 1000000 mole per second.

Embodiment 21. The method of any one of embodiments 16-20, wherein theratio is based on the second continuous stream comprising air.

Embodiment 22. The method of any one of embodiments 16-21, wherein theratio is based on the first continuous stream comprising the hydrogenand the nitrogen from the ammonia reformer.

Embodiment 23. The method of any one of embodiments 16-22, wherein theanode projected surface area comprises the largest possible surface areaof the anode projected onto a flat plane.

Embodiment 24. The method of any one of embodiments 16-23, wherein theanode projected surface area comprises a surface area of the largestsurface of the anode.

Embodiment 25. A method for generating electricity using a fuel cell,comprising: reacting, using an ammonia reformer, ammonia to generate afirst continuous stream comprising nitrogen and hydrogen, wherein theammonia reformer is in fluid communication with a fuel cell, the fuelcell comprising: an electrochemical circuit comprising an anode, acathode, and an electrolyte between the anode and the cathode; a firstchannel comprising a first inlet and a first outlet, wherein the firstchannel is in fluid communication with the anode, wherein the firstchannel comprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof, and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and directing thefirst continuous stream into the first channel via the first inlet sothat the hydrogen contacts the anode; directing a second continuousstream comprising oxygen into the second channel via the second inlet sothat the oxygen contacts the cathode; and reacting the hydrogen and theoxygen, using the fuel cell, to generate electrical power that is atleast 50% of a reference electrical power, wherein the referenceelectrical power is generated using the fuel cell receiving a streamcomprising at least 99% hydrogen by moles into the first inlet, whereinthe electrical power is generated at a same current or a same hydrogenconsumption rate as the reference electrical power.

Embodiment 26. The method of embodiment 25, wherein the electrical poweris at least 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99% ofthe reference electrical power.

Embodiment 27. The method of embodiment 25 or 26, wherein the electricalpower is at most 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%of the reference electrical power.

Embodiment 28. A method for generating electricity using a fuel cell,comprising: reacting, using an ammonia reformer, ammonia to generate afirst continuous stream comprising nitrogen and hydrogen, wherein theammonia reformer is in fluid communication with a fuel cell, wherein thefuel cell comprises: an electrochemical circuit comprising an anode, acathode, and an electrolyte between the anode and the cathode; a firstchannel comprising a first inlet and a first outlet, wherein the firstchannel is in fluid communication with the anode, wherein the firstchannel comprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof, wherein the one or morefeatures comprise a depth less than 10 mm; and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and directing thefirst continuous stream into the first channel via the first inlet sothat the hydrogen contacts the anode; directing a second continuousstream comprising oxygen into the second channel via the second inlet sothat the oxygen contacts the cathode; and reacting the hydrogen and theoxygen, using the fuel cell, to generate electrical power.

Embodiment 29. The method of embodiment 28, wherein the one or morefeatures comprises a depth less than 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6,0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02,or 0.01 mm.

Embodiment 30. The method of embodiment 28 or 29, wherein the one ormore features comprises a depth greater than 5, 4, 3, 2, 1, 0.9, 0.8,0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04,0.03, 0.02, or 0.01 mm.

Embodiment 31. The method of any one of embodiments 28-30, wherein thedepth is at least 1/32, 1/16, ⅛, ¼, ½, ¾, ⅞, 15/16, or 31/32 of thethickness of the first channel.

Embodiment 32. The method of any one of embodiments 28-31, wherein thedepth is at most 1/32, 1/16, ⅛, ¼, ½, ¾, ⅞, 15/16, or 31/32 of thethickness of the first channel.

Embodiment 33. The method of any one of embodiments 28-32, wherein thefirst channel comprises a ratio of a first projected surface area of theone or more features to a second projected surface area of the firstchannel that is at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

Embodiment 34. The method of any one of embodiments 28-33, wherein thefirst channel comprises a ratio of a first projected surface area of theone or more features to a second projected surface area of the firstchannel that is at most 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

Embodiment 35. The method of any one of embodiments 1-34, wherein theone or more features comprise two or more features.

Embodiment 36. The method of embodiment 35, wherein at least a firstsegment of a first feature of the two or more features is substantiallyparallel to a second segment of a second feature of the two or morefeatures.

Embodiment 37. The method of embodiment 35, wherein at least a firstsegment of a first feature of the two or more features is substantiallyperpendicular to a second segment of a second feature of the two or morefeatures.

Embodiment 38. The method of embodiment 35, wherein at least a firstsegment of a first feature of the two or more features is at an angle toa second segment of a second feature of the two or more features,wherein the angle is between 0 and 90 degrees, between 15 and 75degrees, between 0 and 30 degrees, or between 30 and 60 degrees.

Embodiment 39. The method of any one of embodiments 35-38, wherein thetwo or more features are connected.

Embodiment 40. The method of any one of embodiments 35-38, wherein thetwo or more features are disconnected.

Embodiment 41. The method of any one of embodiments 35-38, wherein thetwo or more features intersect.

Embodiment 42. The method of any one of embodiments 1-41, wherein theone or more features comprise a serpentine shape.

Embodiment 43. The method of any one of embodiments 1-42, wherein theone or more features are substantially parallel with the longest side ofthe first channel.

Embodiment 44. The method of any one of embodiments 1-42, wherein theone or more features are substantially parallel with the shortest sideof the first channel.

Embodiment 45. The method of any one of embodiments 1-44, wherein thefuel cell comprises a plurality of channels in fluid communication withthe anode, wherein the plurality of channels comprise the first channel.

Embodiment 46. The method of embodiment 45, wherein the plurality ofchannels comprises a stack of layers that are adjacent to one another.

Embodiment 47. The method of embodiment 45 or 46, wherein at least onechannel in the plurality of channels does not comprise or lacks the oneor more features comprising (i) one or more cuts, (ii) one or morecutouts, (iii) one or more grooves, or (iv) any combination thereof.

Embodiment 48. The method of any one of embodiments 1-47, wherein theone or more features are further configured to facilitate purging of aselect material from the anode gas diffusion layer, wherein the selectmaterial comprises one or more of nitrogen, ammonia, water, or one ormore impurities.

Embodiment 49. The method of embodiment 48, wherein the fuel cellfurther comprises one or more exit ports for discharging the selectmaterial and unconverted hydrogen from the fuel cell.

Embodiment 50. The method of any one of embodiments 1-49, wherein thefirst channel comprises a felt, a foam, a cloth, or a paper material.

Embodiment 51. The method of embodiment 50, wherein the felt, the foam,the cloth, or the paper material is a carbon-based material.

Embodiment 52. The method of any one of embodiments 1-51, wherein theone or more features extend across at least a portion of the surface ofthe first channel.

Embodiment 53. The method of any one of embodiments 1-52, wherein theelectrolyte comprises a proton-exchange membrane.

Embodiment 54. The method of any one of embodiments 1-53, wherein theone or more features are configured to purge nitrogen from the fuel cellwhile the fuel cell is generating electricity.

Embodiment 55. The method of any one of embodiments 1-54, wherein aconcentration of ammonia in the first continuous stream is at most 1000,900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30,20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm.

Embodiment 56. The method of any one of embodiments 1-55, wherein aconcentration of ammonia in the first continuous stream is at least1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50,40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm.

Embodiment 57. The method of any one of embodiments 1-56, wherein theone or more features increase a power density of the fuel cell by atleast 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%.

Embodiment 58. The method of any one of embodiments 1-57, wherein apower density of the fuel cell is at least about 0.1, 0.5, 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

Embodiment 59. The method of any one of embodiments 1-58, wherein apower density of the fuel cell is at most about 0.1, 0.5, 1, 2, 3, 4, 5,6, 7, 8, 9, 10, 20, or 30 kW/L.

Embodiment 60. The method of any one of embodiments 1-59, furthercomprising outputting a third continuous stream comprising unconvertedhydrogen from the fuel cell.

Embodiment 61. The method of embodiment 60, further comprising directingthe third continuous stream comprising the unconverted hydrogen to theammonia reformer.

Embodiment 62. The method of embodiment 61, further comprisingcombusting the unconverted hydrogen to heat the ammonia reformer.

Embodiment 63. The method of embodiment 61 or 62, further comprising,using one or more air supply units, providing at least oxygen to theammonia reformer to combust the unconverted hydrogen in the thirdcontinuous stream.

Embodiment 64. The method of embodiment 62 or 63, further comprisingremoving water in the third continuous stream prior to combusting theunconverted hydrogen.

Embodiment 65. The method of embodiment 60, further comprising flaringthe third continuous stream.

Embodiment 66. The method of any one of embodiments 1-65, wherein thefirst continuous stream comprises at most about 50, 60, 70, 80, 90, 95,99, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7, 99.8, or 99.9% of hydrogenby moles.

Embodiment 67. The method of any one of embodiments 1-66, wherein thefirst continuous stream comprises at least about 50, 60, 70, 80, 90, 95,99, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7, 99.8, or 99.9% of hydrogenby moles.

Embodiment 68. The method of any one of embodiments 1-67, wherein anabsolute pressure of the first continuous stream is at least about 0.5,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or 40 bar.

Embodiment 69. The method of any one of embodiments 1-68, wherein anabsolute pressure of the first continuous stream is at most about 0.5,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or 40 bar.

Embodiment 70. The method of embodiment 68 or 69, further comprisingmaintaining the absolute pressure of the first continuous stream withina tolerance of 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 150,200, 300, 400, 500, or 1000% of the absolute pressure.

Embodiment 71. The method of any one of embodiments 68-70, furthercomprising modulating the absolute pressure of the first continuousstream using one or more flow regulators, pressure regulators, controlunits, or any combination thereof.

Embodiment 72. The method of embodiment 71, wherein the one or more flowregulators, pressure regulators, control units, or any combinationthereof are positioned upstream or downstream of the fuel cell.

Embodiment 73. The method of embodiment 71, further comprisingmodulating a flow rate of the third continuous stream using one or moreflow regulators, pressure regulators, control units, or any combinationthereof.

Embodiment 74. The method of embodiment 73, wherein the one or more flowregulators, pressure regulators, control units, or any combinationthereof are positioned upstream or downstream of the fuel cell.

Embodiment 75. The method of embodiment 73, wherein the one or more flowregulators, pressure regulators, control units, or any combinationthereof are positioned downstream of the fuel cell to prevent a backflow of the unconverted hydrogen.

Embodiment 76. The method of any one of embodiments 1-75, furthercomprising using the generated electrical power to power one or moreelectric devices.

Embodiment 77. The method of any one of embodiments 1-76, furthercomprising using the generated electrical power to power one or moreelectrical grids.

Embodiment 78. The method any one of embodiments 1-77, wherein the fuelcell comprises a plurality of fuel cells, and the ammonia reformerprovides a plurality of streams comprising hydrogen and nitrogen to theplurality of the fuel cells.

Embodiment 79. The method of any one of embodiments 1-78, furthercomprising directing unconverted hydrogen from the plurality of fuelcells to the at least one ammonia reformer or reactor for combustionheating.

Embodiment 80. The method of embodiment 78 or 79, wherein at least onefuel cell of the plurality of fuel cells outputs a different electricalpower than other fuel cells of the plurality of fuel cells.

Embodiment 81. The method of embodiment any one of embodiments 78-80,wherein at least one fuel cell of the plurality of fuel cells isconfigured to reduce an electrical power output.

Embodiment 82. The method of any one of embodiments 78-81, furthercomprising modulating the flow rates of the plurality of streams usingone or more flow regulators, pressure regulators, control units, or anycombination thereof.

Embodiment 83. The method of any one of embodiments 78-82, wherein atleast one fuel cell of the plurality of the fuel cells receives a streamof the plurality of streams, the stream comprising a flow rate that isdifferent from the flow rates of other streams of the plurality ofstreams.

Embodiment 84. The method of any one of embodiments 78-82, wherein eachof the plurality of the fuel cells receives one of the plurality ofstreams at a flow rate that is about the same as or within a selectedtolerance of other flow rates of others of the plurality of streams.

Embodiment 85. The method of embodiment 84, wherein the selectedtolerance is about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%.

Embodiment 86. The method of any one of embodiments 78-85, wherein theplurality of fuel cells comprises at least one fuel cell that isdifferent in size, power output, hydrogen consumption rate, powerdensity, or operating temperature from the other fuel cells.

Embodiment 87. A system comprising: an ammonia reformer configured toreact ammonia to generate a first continuous stream comprising nitrogenand hydrogen; a fuel cell in fluid communication with the ammoniareformer, wherein the fuel cell comprises: an electrochemical circuitcomprising an anode, a cathode, and an electrolyte between the anode andthe cathode; a first channel comprising a first inlet and a firstoutlet, wherein the first channel is in fluid communication with theanode, wherein the first channel comprises one or more featuresconfigured to (i) increase a hydrogen consumption rate, or (ii) increasean output voltage at the same hydrogen consumption rate, when the firstcontinuous stream contacts the anode compared to an equivalent fuel celllacking the one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof, and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and a controllercomprising at least one processor configured to perform executableinstructions, wherein instructions executable by the controller areconfigured to: react the ammonia, using the ammonia reformer, togenerate the first continuous stream comprising hydrogen and nitrogen;direct a second continuous stream comprising oxygen to the cathode ofthe fuel cell; and direct the first continuous stream to the anode ofthe fuel cell to react the hydrogen and oxygen to generate electricity.

Embodiment 88. The system of embodiment 87, wherein the one or morefeatures increase a hydrogen consumption rate of the fuel cell when thefirst continuous stream contacts the anode compared to the equivalentfuel cell lacking the one or more features.

Embodiment 89. The system of embodiment 88, wherein the one or morefeatures increase the hydrogen consumption rate by at least 20, 40, 60,80, 100, 120, 140, 160, 180, or 200%.

Embodiment 90. The system of embodiment 88 or 89, wherein the one ormore features increase the hydrogen consumption rate by at most 20, 40,60, 80, 100, 120, 140, 160, 180, or 200%.

Embodiment 91. The system of any one of embodiments 87-90, wherein theone or more features increase the output voltage at the same hydrogenconsumption rate when the first continuous stream contacts the anodecompared to the equivalent fuel cell lacking the one or more features.

Embodiment 92. The system of embodiment 91, wherein the one or morefeatures increase the output voltage at the same hydrogen consumptionrate by at least 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%.

Embodiment 93. The system of embodiment 91 or 92, wherein the one ormore features increase the hydrogen consumption rate by at most 20, 40,60, 80, 100, 120, 140, 160, 180, or 200%.

Embodiment 94. The system of any one of embodiments 87-93, wherein theone or more features continuously purge nitrogen out of the fuel cell.

Embodiment 95. The system of any one of embodiments 87-94, wherein thenitrogen is continuously directed out of the first channel by the one ormore features so that nitrogen accumulation is reduced in the firstchannel, thereby increasing the hydrogen consumption rate compared tothe equivalent fuel cell lacking the one or more features.

Embodiment 96. The system of any one of embodiments 87-95, wherein thehydrogen consumption rate of the fuel cell when contacting the firstcontinuous stream with the anode is at least about 10, 20, 30, 40, 50,60, 70, 80, 90, or 99% of the hydrogen in the first continuous stream.

Embodiment 97. The system of any one of embodiments 87-96, wherein thehydrogen consumption rate of the fuel cell when contacting the firstcontinuous stream with the anode is at most about 10, 20, 30, 40, 50,60, 70, 80, 90, or 99% of the hydrogen in the first continuous stream.

Embodiment 98. The system of any one of embodiments 87-97, wherein theinstructions executable by the controller are further configured tointermittently reduce the hydrogen consumption rate to purge out atleast one of hydrogen, nitrogen, or water.

Embodiment 99. The system of any one of embodiments 87-98, wherein theinstructions executable by the controller are further configured toreduce the hydrogen consumption rate and direct at least a part of thefirst continuous stream to the ammonia reformer.

Embodiment 100. The system of any one of embodiments 87-99, wherein theinstructions executable by the controller are further configured toreduce the hydrogen consumption rate of the fuel cell to zero and directat least a part of the first continuous stream to the ammonia reformer.

Embodiment 101. The system of embodiment 99 or 100, wherein theinstructions executable by the controller are further configured toflare the at least the part of the first continuous stream directed tothe ammonia reformer at one or more combustion exhausts of one or morecombustion heaters, wherein the one or more combustion heaters are inoperable communication with the ammonia reformer for heating the ammoniareformer, and wherein the one or more combustion heaters are in fluidiccommunication with the fuel to receive the at least the part of thefirst continuous stream.

Embodiment 102. A fuel cell comprising: an electrochemical circuitcomprising an anode, a cathode, and an electrolyte between the anode andthe cathode; a first channel comprising a first inlet and a firstoutlet, wherein the first channel is in fluid communication with theanode, wherein the first channel comprises one or more features, whereinthe one or more features comprise (i) one or more cuts, (ii) one or morecutouts, (iii) one or more grooves, or (iv) any combination thereof; anda second channel comprising a second inlet and a second outlet, whereinthe second channel is in fluid communication with the cathode; whereinthe fuel cell is configured to provide a ratio of an electrical poweroutput of the fuel cell to a projected surface area of the anode that isat least about 0.05 W/cm² when the first inlet is supplied with a firstcontinuous stream comprising about 25% nitrogen and about 75% hydrogenby moles, and the second inlet is supplied with a second continuousstream comprising at least 20% oxygen by moles.

Embodiment 103. The fuel cell of embodiment 102, wherein the ratio is atleast about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4 W/cm².

Embodiment 104. The fuel cell of embodiment 102 or 103, wherein theratio is at most about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4 W/cm².

Embodiment 105. The fuel cell of any one of embodiments 102-104, whereinthe ratio is based on the first continuous stream comprising a hydrogenflow rate of at least about 0.001, 0.01, 0.1, 1, 10, 100, 1000, 10000,100000 mole per second.

Embodiment 106. The fuel cell of any one of embodiments 102-105, whereinthe ratio is based on the second continuous stream comprising an oxygenflow rate of at least about 0.0001, 0.001, 0.01, 0.1, 1, 10, 100, 1000,10000, 100000, 1000000 mole per second.

Embodiment 107. The fuel cell of any one of embodiments 102-106, whereinthe ratio is based on the second continuous stream comprising air.

Embodiment 108. The fuel cell of any one of embodiments 102-107, whereinthe ratio is based on the first continuous stream comprising thehydrogen and the nitrogen from the ammonia reformer.

Embodiment 109. The fuel cell of any one of embodiments 102-108, whereinthe projected surface area of the anode comprises the largest possiblesurface area of the anode projected onto a flat plane.

Embodiment 110. The fuel cell of any one of embodiments 102-109, whereinthe projected surface area of the anode comprises a surface area of thelargest surface of the anode.

Embodiment 111. A fuel cell comprising: an electrochemical circuitcomprising an anode, a cathode, and an electrolyte between the anode andthe cathode; a first channel comprising a first inlet and a firstoutlet, wherein the first channel is in fluid communication with theanode, wherein the first channel comprises one or more features; and asecond channel comprising a second inlet and a second outlet, whereinthe second channel is in fluid communication with the cathode; whereinthe fuel cell is in fluid communication with an ammonia reformerconfigured to provide nitrogen and hydrogen to the fuel cell; andwherein the fuel cell is configured to generate an electrical power atleast 80% of a reference electrical power, wherein the referenceelectrical power is generated using the fuel cell receiving a continuousstream comprising at least 99% hydrogen by moles into the first inlet,wherein the electrical power is generated at a same current or a samehydrogen consumption rate as the reference electrical power.

Embodiment 112. The fuel cell of embodiment 111, wherein the electricalpower is at least 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%of the reference electrical power.

Embodiment 113. The fuel cell of embodiment 111 or 112, wherein theelectrical power is at most 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97,98, or 99% of the reference electrical power.

Embodiment 114. A system comprising: an ammonia reformer; a fuel cell influid communication with the ammonia reformer, wherein the fuel cellcomprises: an electrochemical circuit comprising an anode, a cathode,and an electrolyte between the anode and the cathode; a first channelcomprising a first inlet and a first outlet, wherein the first channelis in fluid communication with the anode, wherein the first channelcomprises one or more features, wherein the one or more featurescomprise (i) one or more cuts, (ii) one or more cutouts, (iii) one ormore grooves, or (iv) any combination thereof, wherein the one or morefeatures comprise a depth less than 10 mm; and a second channelcomprising a second inlet and a second outlet, wherein the secondchannel is in fluid communication with the cathode; and a controllercomprising at least one processor configured to perform executableinstructions, wherein instructions executable by the controller areconfigured to: direct ammonia to the ammonia reformer to generate afirst continuous stream comprising hydrogen and nitrogen; direct asecond continuous stream comprising oxygen to the cathode of the fuelcell; and direct the first continuous stream to the anode of the fuelcell to react the hydrogen and oxygen to generate electricity.

Embodiment 115. The system of embodiment 114, wherein the one or morefeatures comprises a depth less than 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6,0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02,or 0.01 mm.

Embodiment 116. The system of embodiment 114 or 115, wherein the one ormore features comprises a depth greater than 5, 4, 3, 2, 1, 0.9, 0.8,0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04,0.03, 0.02, or 0.01 mm.

Embodiment 117. The system of any one of embodiments 114-116, whereinthe depth is at least 1/32, 1/16, ⅛, ¼, or ½ of the thickness of thefirst channel.

Embodiment 118. The system of any one of embodiments 114-117, whereinthe depth is at most 1/32, 1/16, ⅛, ¼, or ½ of the thickness of thefirst channel.

Embodiment 119. The system of any one of embodiments 114-118, wherein aratio of a first projected surface area of the one or more features to asecond projected surface area of the first channel is at least 0.1, 0.2,0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

Embodiment 120. The system of any one of embodiments 114-119, wherein aratio of a first projected surface area of the one or more features to asecond projected surface area of the first channel is at most 0.1, 0.2,0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

Embodiment 121. The system of any one of embodiments 114-120, whereinthe ammonia reformer generates the first continuous stream additionallycomprising at most 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100,90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm ofammonia.

Embodiment 122. The system of any one of embodiments 114-121, whereinthe ammonia reformer generates the first continuous stream additionallycomprising at least 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100,90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm ofammonia.

Embodiment 123. The system or the fuel cell of any one of embodiments87-122, wherein the one or more features comprises two or more features.

Embodiment 124. The system or the fuel cell of embodiment 123, whereinat least a first segment of a first feature of the two or more featuresis substantially parallel to a second segment of a second feature of thetwo or more features.

Embodiment 125. The system or the fuel cell of embodiment 123, whereinat least a first segment of a first feature of the two or more featuresis substantially perpendicular to a second segment of a second featureof the two or more features.

Embodiment 126. The system or the fuel cell of embodiment 123, whereinat least a first segment of a first feature of the two or more featuresis at an angle to a second segment of a second feature of the two ormore features, wherein the angle is between 0 and 90 degrees, between 15and 75 degrees, between 0 and 30 degrees, or between 30 and 60 degrees.

Embodiment 127. The system or the fuel cell of any one of embodiments123-126, wherein the two or more features are connected.

Embodiment 128. The system or the fuel cell of any one of embodiments123-126, wherein the two or more features are disconnected.

Embodiment 129. The system or the fuel cell of any one of embodiments123-126, wherein the two or more features intersect.

Embodiment 130. The system or the fuel cell of any one of embodiments87-129, wherein the one or more features are fully enclosed by the firstchannel.

Embodiment 131. The system or the fuel cell of any one of embodiments87-129, wherein the one or more features are partially enclosed by thefirst channel.

Embodiment 132. The system or the fuel cell of any one of embodiments87-131, wherein the one or more features comprise a serpentine shape.

Embodiment 133. The system or the fuel cell of any one of embodiments87-132, wherein the one or more features are substantially parallel withthe longest side of the first channel.

Embodiment 134. The system or the fuel cell of any one of embodiments87-132, wherein the one or more features are substantially parallel withthe shortest side of the first channel.

Embodiment 135. The system or the fuel cell of any one of embodiments87-134, wherein the fuel cell comprises a plurality of channels in fluidcommunication with the anode, wherein the plurality of channelscomprises the first channel.

Embodiment 136. The system or the fuel cell of embodiment 135, whereinthe plurality of channels comprises a stack of layers that are adjacentto one another.

Embodiment 137. The system or the fuel cell of embodiment 135 or 136,wherein at least one channel in the plurality of channels does notcomprise or lacks the one or more features comprising (i) one or morecuts, (ii) one or more cutouts, (iii) one or more grooves, or (iv) anycombination thereof.

Embodiment 138. The system or the fuel cell of any one of embodiments87-137, wherein the one or more features are further configured tofacilitate purging of a select material from the anode gas diffusionlayer, wherein the select material comprises one or more of nitrogen,ammonia, water, or one or more impurities.

Embodiment 139. The system or the fuel cell of embodiment 138, whereinthe fuel cell further comprises one or more exit ports for dischargingthe select material and unconverted hydrogen from the fuel cell.

Embodiment 140. The system or the fuel cell of any one of embodiments87-139, wherein the first channel comprises a felt, a foam, a cloth, ora paper material.

Embodiment 141. The system or the fuel cell of embodiment 140, whereinthe felt, the foam, the cloth, or the paper material is a carbon-basedmaterial.

Embodiment 142. The system or the fuel cell of any one of embodiments87-141, wherein the one or more features extend across at least aportion of the surface of the first channel.

Embodiment 143. The system or the fuel cell of any one of embodiments87-142, wherein the electrolyte comprises a proton-exchange membrane.

Embodiment 144. The system or the fuel cell of any one of embodiments87-143, wherein the fuel cell is configured to allow purging of nitrogenfrom the fuel cell while the fuel cell is generating electricity.

Embodiment 145. The system or the fuel cell of any one of embodiments87-144, wherein the first channel is supplied with a stream comprising aconcentration of ammonia of at most 1000, 900, 800, 700, 600, 500, 400,300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3,2, or 1 ppm.

Embodiment 146. The system or the fuel cell of any one of embodiments87-145, wherein the first channel is supplied with a stream comprising aconcentration of ammonia of at least 1000, 900, 800, 700, 600, 500, 400,300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3,2, or 1 ppm.

Embodiment 147. The system or the fuel cell of any one of embodiments87-146, wherein the one or more features increase a power density of thefuel cell by at least 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or200%.

Embodiment 148. The system or the fuel cell of any one of embodiments87-147, wherein a power density of the fuel cell is at least about 0.1,0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

Embodiment 149. The system or the fuel cell of any one of embodiments87-148, wherein a power density of the fuel cell is at most about 0.1,0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

Embodiment 150. The system or the fuel cell of embodiment 149, furthercomprising one or more combustion heaters for combusting an exit streamoutput by the fuel cell to heat the ammonia reformer, wherein the exitstream comprises unconverted hydrogen.

Embodiment 151. The system or the fuel cell of embodiment 150, furthercomprising one or more air supply units for providing at least oxygen tothe one or more combustion heaters.

Embodiment 152. The system or the fuel cell of embodiment 149 or 150,further comprising one or more dehydrators for removing water in theexit stream in prior to combusting the unconverted hydrogen.

Embodiment 153. The system or the fuel cell of embodiment 150, whereinthe system is configured to flare the unconverted hydrogen at acombustion exhaust of the one or more combustion heaters.

Embodiment 154. The system or the fuel cell of any one of embodiments87-153, further comprising one or more flow regulators, pressureregulators, control units, or any combination thereof for modulating anabsolute pressure of an input stream or an output stream of the fuelcell.

Embodiment 155. The system or the fuel cell of embodiment 154, whereinthe one or more flow regulators, pressure regulators, control units, orany combination thereof are positioned upstream or downstream of thefuel cell.

Embodiment 156. The system or the fuel cell of embodiment 154 or 155,wherein the one or more flow regulators, pressure regulators, controlunits, or any combination thereof are positioned downstream of the fuelcell to reduce or prevent a back flow of the unconverted hydrogen.

Embodiment 157. The system or the fuel cell of any one of embodiments87-156, further comprising an electrical load connected to theelectrochemical circuit.

Embodiment 158. The system or the fuel cell of embodiment 157, whereinthe electrical load comprises one or more electric devices.

Embodiment 159. The system or the fuel cell of embodiment 158, whereinthe electrical load comprises one or more electrical grids.

Embodiment 160. The system or the fuel cell of embodiment 158, whereinthe electrical load comprises an engine or a motor.

Embodiment 161. The system or the fuel cell of any one of embodiments87-160, wherein the fuel cell comprises a plurality of fuel cells inoperable communication with the ammonia reformer, the ammonia reformerconfigured to provide a plurality of streams comprising hydrogen andnitrogen to the plurality of the fuel cells.

Embodiment 162. The system or the fuel cell of embodiment 161, whereinthe system is configured to direct unconverted hydrogen from theplurality of fuel cells to one or more combustors in thermalcommunication with the ammonia reformer.

Embodiment 163. The system or the fuel cell of embodiment 161 or 162,wherein at least one fuel cell of the plurality of fuel cells comprisesa different electrical power output than other fuel cells of theplurality of fuel cells.

Embodiment 164. The system or the fuel cell of any one of embodiments161-163, wherein at least one fuel cell of the plurality of fuel cellsis configured to reduce an electrical power output.

Embodiment 165. The system or the fuel cell of any one of embodiments161-164, wherein one or more ammonia reformers in fluid communicationwith the plurality of fuel cells provide to at least one fuel cell ofthe plurality of the fuel cells a stream that comprises a flow rate thatis different from the flow rate of another stream provided to anotherfuel cell.

Embodiment 166. The system or the fuel cell of any one of embodiments161-164, wherein one or more ammonia reformers in fluid communicationwith the plurality of fuel cells are configured to provide a pluralityof streams to the plurality of fuel cells, wherein the flow rates of theplurality of streams is about the same as or within a selected toleranceof other flow rates of others of the plurality of streams.

Embodiment 167. The system or the fuel cell of embodiment 166, whereinthe selected tolerance is about 10, 20, 30, 40, 50, 60, 70, 80, 90, or100%.

Embodiment 168. The system or the fuel cell of any one of embodiment161-167, wherein the plurality of fuel cells comprises at least one fuelcell that is different in size, power output, hydrogen consumption rate,power density, or operating temperature from the other fuel cells.

Embodiment 169. A fuel cell, comprising: an anode; a cathode; and amembrane between the anode and the cathode, wherein the anode comprisesan anode gas diffusion layer with one or more channels for directing asource material comprising hydrogen and nitrogen to the anode forprocessing of the source material to generate an electrical current,wherein the one or more channels comprise one or more featurescomprising (i) one or more cuts, (ii) one or more cutouts, or (iii) oneor more grooves configured to enhance diffusion and transport of thesource material through the anode gas diffusion layer, and wherein theone or more features are configured to direct a flow of nitrogen fromthe anode gas diffusion layer to out of the fuel cell so that nitrogendoes not accumulate in the anode gas diffusion layer.

Embodiment 170. The fuel cell of embodiment 169, wherein the one or morefeatures comprise two or more features.

Embodiment 171. The fuel cell of embodiment 169 or 170, wherein the oneor more features are further configured to facilitate purging of aselect material from the anode gas diffusion layer, wherein the selectmaterial comprises one or more of nitrogen, ammonia, water, or one ormore impurities.

Embodiment 172. The fuel cell of embodiment 171, further comprising oneor more exit ports for discharging the select material and unconvertedhydrogen from the fuel cell.

Embodiment 173. The fuel cell of any one of embodiments 169-172, whereinthe processing of the source material comprises a dissociation of one ormore hydrogen molecules of the source material into one or more protonsand one or more electrons.

Embodiment 174. The fuel cell of any one of embodiments 169-173, whereinthe anode gas diffusion layer comprises a felt, a foam, a cloth, or apaper material.

Embodiment 175. The fuel cell of embodiment 174, wherein the felt, thefoam, the cloth, or the paper material is a carbon-based material.

Embodiment 176. The fuel cell of any one of embodiments 169-175, whereinthe one or more features extend across at least a portion of the surfaceof the one or more channels.

Embodiment 177. The fuel cell of any one of embodiments 170-176, whereinthe two or more features are parallel to each other.

Embodiment 178. The fuel cell of any one of embodiments 170-177, whereinthe two or more features are perpendicular to each other.

Embodiment 179. The fuel cell of any one of embodiments 170-178, whereinthe two or more features are disposed at an angle relative to eachother, wherein the angle ranges from 0 degrees to 90 degrees.

Embodiment 180. The fuel cell of any one of embodiments 170-179, whereinthe two or more features intersect with each other.

Embodiment 181. The fuel cell of any one of embodiments 170-180, whereinthe two or more features do not intersect.

Embodiment 182. The fuel cell of any one of embodiments 169-181, whereinthe anode gas diffusion layer comprises a plurality of layers.

Embodiment 183. The fuel cell of any one of embodiments 169-182, whereinat least one layer of the plurality of layers comprises the one or morechannels comprising the one or more features.

Embodiment 184. The fuel cell of embodiment 183, wherein the pluralityof layers comprises a first layer comprising a first set of features anda second layer comprising a second set of features.

Embodiment 185. The fuel cell of embodiment 184, wherein the first setof features and the second set of features comprise a same or similarset of features.

Embodiment 186. The fuel cell of embodiment 184 or 185, wherein thefirst set of features and the second set of features comprise differentsets of features having different shapes, dimensions, positions, ororientations.

Embodiment 187. The fuel cell of any one of embodiments 184-186, whereinthe first set of features and the second set of features overlap orpartially overlap.

Embodiment 188. The fuel cell of any one of embodiments 184-186, whereinthe first set of features and the second set of features do not overlap.

Embodiment 189. The fuel cell of any one of embodiments 169-188, whereinat least one feature of the one or more features has a depth rangingfrom about 0.01 millimeter (mm) to about 10 mm.

Embodiment 190. A fuel cell system, comprising: a plurality of fuelcells comprising the fuel cell of any one of embodiments 169-189, atleast one ammonia reformer or reactor in fluid communication with theplurality of fuel cells, wherein the at least one ammonia reformer orreactor is configured to (i) generate the source material and (ii)provide the source material to the fuel cell.

Embodiment 191. The fuel cell system of embodiment 190, wherein theplurality of fuel cells are arranged (i) adjacent to each other in alateral configuration or (ii) on top of each other in a stackedconfiguration.

Embodiment 192. The fuel cell system of embodiment 190 or 191, whereinthe plurality of fuel cells comprises at least one proton-exchangemembrane fuel cell (PEMFC).

Embodiment 193. A fuel cell system comprising the fuel cell of any oneof embodiments 169-192, wherein the fuel cell system comprises acontroller configured to operate the fuel cell to allow purging ofnitrogen from the fuel cell while the fuel cell is generatingelectricity.

Embodiment 194. The fuel cell system of any one of embodiments 190-193,further comprising a controller configured to operate the fuel cell toallow purging of nitrogen from the fuel cell while the fuel cell isgenerating electricity.

Embodiment 195. The fuel cell system of any one of embodiments 190-194,wherein at least one feature of the one or more features has a depthranging from about 0.01 millimeter (mm) to about 10 mm.

Embodiment 196. The fuel cell system of any one of embodiments 190-195,wherein the fuel cell system further comprises one or more inlet portsconfigured to receive the source material, wherein ammonia concentrationin the source material is less than 1 ppm.

Embodiment 197. The fuel cell system of any one of embodiments 190-196,wherein the fuel cell system further comprises one or more exit portsconfigured to direct unconverted hydrogen from the plurality of fuelcells to the at least one ammonia reformer or reactor, wherein theunconverted hydrogen is combusted to heat the ammonia reformer orreactor.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. It is not intendedthat the invention be limited by the specific examples provided withinthe specification. While the invention has been described with referenceto the aforementioned specification, the descriptions and illustrationsof the embodiments herein are not meant to be construed in a limitingsense. Numerous variations, changes, and substitutions will now occur tothose skilled in the art without departing from the invention.Furthermore, it shall be understood that all aspects of the inventionare not limited to the specific depictions, configurations or relativeproportions set forth herein which depend upon a variety of conditionsand variables. It should be understood that various alternatives to theembodiments of the invention described herein may be employed inpracticing the invention. It is therefore contemplated that theinvention shall also cover any such alternatives, modifications,variations or equivalents. It is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

1. A method comprising: using an ammonia reformer to generate a firststream comprising hydrogen and nitrogen; directing the first stream anda second stream comprising oxygen to a fuel cell, wherein the fuel cellis in fluid communication with the ammonia reformer, wherein the fuelcell comprises: an electrochemical circuit comprising an anode, acathode, and an electrolyte between the anode and the cathode; and achannel in fluid communication with the anode, wherein the channelcomprises an inlet configured to receive the first stream comprisingnitrogen and hydrogen, wherein the channel further comprises one or morefeatures which are configured to purge nitrogen from the fuel cell whilethe fuel cell is generating electricity, wherein a volume fraction ofthe hydrogen in the first stream comprises at most about 85%, wherein avolume fraction of the nitrogen in the first stream comprises at leastabout 15%; directing the hydrogen through the channel to the anode toreact with the oxygen, thereby generating electricity; and purgingnitrogen out of the fuel cell.
 2. The method of claim 1, wherein ahydrogen consumption rate of the fuel cell is at least about 20% of thehydrogen in the first stream.
 3. The method of claim 1, wherein ahydrogen consumption rate of the fuel cell is intermittently reduced topurge out at least one of hydrogen, nitrogen, or water.
 4. The method ofclaim 1, wherein the fuel cell comprises a plurality of channels influid communication with the anode, wherein the plurality of channelscomprises the channel.
 5. The method of claim 4, wherein the pluralityof channels comprises a stack of layers that are adjacent to oneanother.
 6. The method of claim 1, wherein the fuel cell furthercomprises a second channel in fluid communication with the anode,wherein the second channel comprises a second inlet configured toreceive the first stream comprising nitrogen and hydrogen, wherein thesecond channel does not comprise or lacks the one or more features. 7.The method of claim 1, wherein the fuel cell is configured to outputunconverted hydrogen from the fuel cell.
 8. The method of claim 7,wherein the unconverted hydrogen is combusted to heat the ammoniareformer.
 9. The method of claim 7, wherein the unconverted hydrogen isflared.
 10. The method of claim 1, wherein the fuel cell comprises aplurality of fuel cells, wherein at least one fuel cell of the pluralityof fuel cells is configured to reduce an electrical power output whileothers of the plurality of fuel cells maintain their respective poweroutputs.
 11. The method of claim 1, wherein at least part of the firststream is directed to a combustion heater to reduce a portion of thehydrogen in the first stream that is reacted in the fuel cell, therebyreducing a hydrogen consumption rate of the fuel cell, reducing theelectricity generated by the fuel cell, and purging nitrogen out of thefuel cell, wherein the combustion heater is in thermal communicationwith the ammonia reformer, wherein the at least part of the first streamis directed to the combustion heater based at least in part on atemperature of the ammonia reformer.
 12. The method of claim 1, whereina hydrogen consumption rate of the fuel cell is intermittently reducedto purge out hydrogen, nitrogen, and water.
 13. The method of claim 1,wherein the one or more features are parallel to each other.
 14. Themethod of claim 1, wherein the one or more features are perpendicular toeach other.
 15. The method of claim 1, wherein the one or more featuresare disposed at an angle relative to each other, wherein the angleranges from about 0 degree to about 90 degrees.
 16. The method of claim1, wherein the one or more features intersect with each other.
 17. Themethod of claim 1, wherein the one or more features do not intersect.18. The method of claim 1, wherein the one or more features have a depthranging from about 0.01 millimeter (mm) to about 10 mm.
 19. The methodof claim 1, wherein an ammonia concentration in the first stream is lessthan about 1 parts-per-million (ppm).
 20. A system comprising: (a) anammonia reformer configured to convert ammonia into a first streamcomprising nitrogen and hydrogen; (b) a fuel cell in fluid communicationwith the ammonia reformer, wherein the fuel cell comprises: i. anelectrochemical circuit comprising an anode, a cathode, and anelectrolyte between the anode and the cathode; and ii. a channel influid communication with the anode, wherein the channel comprises aninlet configured to receive the first stream comprising nitrogen andhydrogen, wherein the channel further comprises one or more featureswhich are configured to purge nitrogen from the fuel cell while the fuelcell is generating electricity; wherein the fuel cell comprises aplurality of fuel cells, wherein at least one fuel cell of the pluralityof fuel cells is configured to reduce an electrical power output whileothers of the plurality of fuel cells maintain their respective poweroutputs; and (c) a controller comprising at least one processorconfigured to perform executable instructions, wherein the executableinstructions are configured to: i. use the ammonia reformer to generatethe first stream comprising hydrogen and nitrogen; ii. direct a secondstream comprising oxygen to the cathode; iii. direct the first streamthrough the channel to the anode to react the hydrogen with the oxygen,thereby generating electricity; and iv. direct at least part of thefirst stream to a combustion heater to reduce a portion of hydrogen inthe first stream that is reacted in the at least one fuel cell, therebyreducing a hydrogen consumption rate of the at least one fuel cell,reducing the electrical power output of the at least one fuel cell, andpurging nitrogen out of the at least one fuel cell, wherein thecombustion heater is in thermal communication with the ammonia reformer,wherein the at least part of the first stream is directed to thecombustion heater based at least in part on a temperature of the ammoniareformer.
 21. The system of claim 20, wherein a hydrogen consumptionrate of the fuel cell is at least about 20% of the hydrogen in the firststream.
 22. The system of claim 20, wherein the executable instructionsare further configured to intermittently reduce a hydrogen consumptionrate of the fuel cell to purge out at least one of hydrogen, nitrogen,or water.
 23. The system of claim 20, wherein the executableinstructions are further configured to intermittently reduce a hydrogenconsumption rate of the fuel cell to purge out hydrogen, nitrogen, andwater.
 24. The system of claim 20, wherein the fuel cell comprises aplurality of channels in fluid communication with the anode, wherein theplurality of channels comprises the channel.
 25. The system of claim 24,wherein the plurality of channels comprises a stack of layers that areadjacent to one another.
 26. The system of claim 20, wherein the fuelcell further comprises a second channel in fluid communication with theanode, wherein the second channel comprises a second inlet configured toreceive the first stream comprising nitrogen and hydrogen, wherein thesecond channel does not comprise or lacks the one or more features. 27.The system of claim 20, wherein the fuel cell is configured to outputunconverted hydrogen from the fuel cell.
 28. The system of claim 27,wherein the unconverted hydrogen is combusted to heat the ammoniareformer.
 29. The system of claim 27, wherein the unconverted hydrogenis flared.
 30. The system of claim 20, wherein a volume fraction of thehydrogen in the first stream comprises at most about 85%, wherein avolume fraction of the nitrogen in the first stream comprises at leastabout 15%.